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PubMed2004

Effect of breeder age and breeding season on egg production and incubation in farmed ostriches.

(1) This research was carried out to investigate changes in egg production and hatchability as influenced by age and breeding season of 10 trios (two females, one male) of ostrich (Struthio camellus) during 1998 to 2002. (2) Breeding season affected number of eggs laid per female per season, average egg weight, length of laying period and clutch sequence. (3) The number of eggs laid per female per season was 25 in the first breeding season and 57 by the fifth breeding season. The laying period lasted 169 d in the first season whereas it was 210 d by the fifth season. The breeding season became longer year by year. (4) The number of clutches was two in the first season, three in the second and 4 in the later breeding seasons: the mean interval between cycles was 9 to 10.6 d and the mean number of eggs in one cycle varied from 12 to 14.4. (5) The breeding season affected the hatchability of fertile eggs, chick weight at hatching, hatchability of total eggs, fertility, malpositioned embryos, deformed chicks and assisted chicks during hatching. The first 4 variables increased and the last three decreased, with each breeding season. (6) Weight loss of eggs and length of incubation were unaffected by the breeding season. Hatchability which was 64.3% in the first season increased progressively and reached 73.1% in the fifth breeding season.

Aging↗
PubMed1994

[Hypothalamo-pituitary-testicular function in male Japanese monkeys (Macaca fuscata) in non-mating season].

We examined seasonal changes in serum testosterone and LH, and investigated mechanisms of reduction of testicular function in non-mating season in male Japanese monkeys. Blood samples were collected monthly throughout one year in 5 males, and hCG and LH-RH were administered to 5 and 3 animals, respectively, in non-mating and mating season. Serum testosterone and LH were measured by RIA. Serum testosterone showed the obvious seasonal changes, being low in March to August and high in October to February. Also we found the seasonal changes in LH being low in May to August and high in September to February. When hCG was administered to 5 monkeys in mating season (January), serum testosterone levels increased markedly 30 to 180 min after single administration and showed further increases after continuous administrations for four days. However, in non-mating season (August), serum testosterone showed a little increase for the same treatment as in mating season. These data showed that the reserve ability of testosterone secretion in testis in non-mating season decreased obviously in contrast to mating season. The increase of serum LH and testosterone levels in 3 males in non-mating season (July) after LH-RH single administration were less than those in mating season (December). In intermediate period (September) between non-mating season and mating season, LH showed higher level than that in mating season but the testosterone level was the same extent as in non-mating season.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed2005

Seasonality in a community sample of bipolar, unipolar and control subjects.

BACKGROUND: This study examined seasonality in a community sample of five diagnostic groups: normal subjects, those with non-seasonal depression (NSD), seasonal depression (SD), non-seasonal bipolar disorder (NSBD) and seasonal bipolar disorder (SBD). METHODS: Telephone interviews were conducted across the Province of Ontario. Seasonal changes in mood and behaviour were determined using the Seasonal Pattern Assessment Questionnaire (SPAQ). Five additional seasonality items consisting of depressive symptoms were included in the interview. The mean global severity of seasonality (GSS) scores were obtained and the entire inventory of 11 seasonality items were compared across the identified groups. RESULTS: The mean GSS score for the controls was 5.2 (S.D. = 4.0), 8.0 (S.D. = 4.9) for NSD, 10.5 (S.D. = 3.9) for SD, 10.5 (S.D. = 5.4) for NSBD and 13.4 (S.D. = 5.4) for SBD. These scores differed significantly (F = 61.68, df = 4, p < 0.001). For the majority of the individual items, the SBD group rated the highest degree of seasonal fluctuation, while the NSBD and SD groups had nearly identical item scores. LIMITATIONS: Limitations in this study include the relatively small number of subjects in the NSBD and SBD groups, and the inherent limitations in a telephone interview. CONCLUSIONS: Individuals with bipolar disorder experience greater seasonality than those with depression or healthy controls. Even the non-seasonal bipolar group had as much seasonal fluctuation as the seasonal depression group, which has important implications for the management of bipolar illness.

Adult↗
PubMed1995

A longitudinal follow-up study of seasonal affective disorder.

OBJECTIVE: The purposes of this study were to evaluate the long-term stability of a seasonal pattern of recurrent depression, identify possible factors associated with alteration of the seasonal pattern, and determine whether atypical vegetative symptoms during early seasonal depressive episodes predict future seasonal relapses. METHOD: The subjects were 41 patients satisfying the criteria used in the Japanese multicenter study of seasonal affective disorder who were consistently treated at the same outpatient clinic. Their longitudinal courses were evaluated by using case records and the Schedule for Affective Disorder and Schizophrenia--Life-time Version; the mean follow-up period was 10.4 years. RESULTS: Nine subjects (22.0%) consistently showed a fall-winter pattern of recurrence throughout follow-up. Seventeen patients with an initial fall-winter pattern subsequently tended to shift seasons or show less seasonality. This alteration in pattern was possibly associated with antidepressant therapy or life events. Eleven patients with an initial diagnosis of nonseasonal affective disorder subsequently developed seasonal affective disorder; no specific factors were associated with this change. Atypical vegetative symptoms were significantly more common in patients with stable seasonal patterns of recurrence than in those who lost seasonality. CONCLUSIONS: Although seasonal affective disorder appeared to be altered by antidepressant treatment, the presence of a core group of patients with a consistent seasonal pattern of recurrent depression suggests the validity of seasonal affective disorder as a distinct subtype of recurrent affective illness. The findings also suggest that atypical vegetative symptoms during early seasonal depressive episodes predict the subsequent seasonality of depression.

Adult↗
PubMed2000

Foraging energetics in patas monkeys (Erythrocebus patas) and tantalus monkeys (Cercopithecus aethiops tantalus): implications for reproductive seasonality.

The patas monkeys (Erythrocebus patas) in Kala Maloue, Cameroon, have their birth season in the mid-dry season, whereas closely related, sympatric tantalus monkeys (Cercopithecus aethiops tantalus) have their birth season in the wet season. To evaluate the optimality of a species-specific birth season, I estimated the daily intake of available energy and gross protein, and energy expenditure for one individual of each sex of each species between respective birth and mating seasons. The monkeys obtained a larger amount of available energy and gross protein in the birth season than in the mating season. No significant seasonal differences in energy expenditure between the birth and mating season were found. Thus, the birth season appears to be timed to the season when the monkeys can obtain more surplus energy and protein. Interspecific differences in the optimality of birth season were attributed to widely exploitative foraging, supported by the patas' high locomotive ability, which may enable them to obtain more energy from seeds of Acacia seyal and gums of A. sieberiana, and more protein from grasshoppers and seeds of A. seyal in the mid-dry season than the tantalus monkeys. A review of preceding studies suggests that the availability of seeds of Acacia fruiting during the dry season may exert the dominant influence on timing of birth not only in patas but also in savanna monkeys (Cercopithecus aethiops), which include the tantalus monkeys.

Animals↗
PubMed2003

Rice-based diets in rural Bangladesh: how do different age and sex groups adapt to seasonal changes in energy intake?

BACKGROUND: Seasonality has been recognized as a key determinant of human energy balance, especially in low-income countries. OBJECTIVE: The objective was to test the hypothesis that, in rural Bangladesh, different age and sex groups adapt similarly to seasonal changes in energy intake (EI). DESIGN: A prospective study was carried out in 2 rural Bangladeshi villages in the lean and peak seasons. Data on anthropometric measures (weight, height, and midupper arm circumference) and dietary food intake (collected with the use of a 24-h food weighing method) were obtained from all subjects from 304 households. RESULTS: The average EI increased from a least-squares mean (+/- SE) of 7.87 +/- 0.10 MJ x person(-1) x d(-1) in the lean season to 9.47 +/- 0.13 MJ x person(-1) x d(-1) in the peak season. In children and adolescents aged < 18 y of age, the prevalence of underweight (weight-for-age) was not significantly different (56%) in the 2 seasons. Among adults, a significantly higher prevalence of chronic energy deficiency [body mass index (in kg/m(2)) < 18.5] was observed in the peak season (67%) than in the lean season (61%), despite a higher EI in the peak season. Other determinants of seasonal nutritional status are presented. CONCLUSIONS: Seasonal fluctuations in EI were substantial in all age and sex groups. Children and adolescents showed no significant seasonal changes in the prevalence of underweight, which indicated that they adapted to changes in EI. In adults, the season in which EI was high coincided with average weight loss, which indicated that adults did not adapt fully to seasonal fluctuations in EI and that seasonal energy expenditure is probably a major determinant of nutritional status.

Adaptation, Physiological↗
PubMed2001

Daily and seasonal patterns of carbon and water fluxes above a north Australian savanna.

Daily and seasonal fluxes of carbon dioxide and water vapor above a north Australian savanna were recorded over a complete dry season-wet season annual cycle using the eddy covariance technique. Wet season rates of photosynthesis and transpiration were larger than those measured in the dry season and were dominated by the presence of the grassy understory. As the dry season progressed and the grass understory died, ecosystem rates of assimilation and water vapor flux declined substantially. By the end of the dry season, canopy assimilation and evapotranspiration rates were 20-25% of wet season values. Assimilation was light saturated in the dry season but not in the wet season. Stomatal control of transpiration increased between the wet and dry season. This was revealed by the decline in the slope of E with increasing leaf-to-air vapor pressure difference (D) between wet and dry seasons, and also by the significant decrease in the ratio of boundary to canopy conductance observed between the wet and dry seasons. A simple pan-tropical modeling of leaf area index or wet season canopy CO2 flux was undertaken. It was shown that with readily available data for foliar N content and the ratio of rainfall to potential evaporation, leaf index and wet season canopy CO2 flux can be successfully estimated for a number of tropical ecosystems, including north Australian savannas.

Atmosphere↗
PubMed1991

Marked seasonal changes in response to the negative feedback action of estradiol on luteinizing hormone secretion in the female Japanese monkey.

The seasonal changes in response to the negative feedback action of estradiol on LH secretion were studied in two groups of ovariectomized Japanese monkeys (Macaca fuscata fuscata; n = 6). Blood samples were collected two to three times a week, and changes in serum concentrations of LH, estradiol, and progesterone were examined. Before ovariectomy (OVX), serum LH was maintained at about 320 pg/ml regardless of the season (breeding season: autumn and winter). After OVX and simultaneous treatment sc with a Silastic implant of estradiol during the first breeding season, serum LH increased rapidly and remained high. As spring arrived, serum LH decreased abruptly and remained low. The removal of implants during the subsequent nonbreeding season resulted in an increase in serum LH similar to that during the previous breeding season after OVX and estradiol treatment. After the reinsertion of implants during the same nonbreeding season, serum LH reverted to previous low levels. As autumn arrived (second breeding season), serum LH rose again and remained high under the presence of implants. In the first subset of animals (n = 3), the implants were left in place until the subsequent mid-nonbreeding season when they were removed, and reinserted during the same non-breeding season. The findings closely corresponded to the previous results. In these animals, the implants were removed during the third breeding season, which resulted in a significant increase in serum LH. The second subset of animals (n = 3) underwent removal of implants during the second breeding season, which resulted in a further increase in serum LH, but the difference was not significant. In both subsets of animals, the timing of the increase and decrease in serum LH under the presence of implants virtually coincided with the onset and end of the breeding season in ovary-intact animals. Serum estradiol after OVX was maintained at levels similar to those in intact animals (80-100 pg/ml) under the presence of implants, but removal of implants resulted in decrease in serum estradiol to around 30 pg/ml within 1 week. Serum progesterone after OVX was maintained at low levels (less than 0.2 ng/ml) regardless of the presence of estradiol implants. These results clearly indicate a marked seasonal difference in serum LH concentrations in ovariectomized monkeys in response to constant serum estradiol. It is suggested that seasonal breeding of the Japanese monkey is governed by biannual changes in the response of the hypothalamo-hypophysial axis to the negative feedback action of estradiol.

Animals↗
PubMed1985

Changes in pulsatile LH secretion after ovariectomy in Ile-de-France ewes in two seasons.

Two experiments were conducted in Ile-de-France ewes to study changes in pulsatile LH secretion in ewes ovariectomized during anoestrus or during the midluteal phase of the oestrous cycle. In Exp. 1, blood samples were taken every 20 min for 12 h the day before ovariectomy (Day 0). After ovariectomy, samples were taken every 10 min for 6 h (10 ewes per group), on Days 1, 3, 7 and 15. In Exp. 2 samples were taken every 10 min for 6 h (10 ewes per group) on Days 7, 15, 30, 60, 90, 120, 150 and 180 after ovariectomy. Further samples were taken (5 ewes per group) at 9 and 12 months after ovariectomy. There were significant interactions between season and day of sampling for the interval between LH pulses in both experiments. LH pulse frequency increased within 1 day of ovariectomy and the increase was more rapid during the breeding season. There were clear seasonal differences in pulse frequency in Exp. 2. Compared with ewes ovariectomized in anoestrus, pulse frequency was significantly higher for ewes ovariectomized in the breeding season, from Day 7 until Day 120. Once pulse frequency had increased in ewes about the time of the normal breeding season, pulse frequency remained high and subsequent seasonal changes were greatly reduced. Pulse amplitude increased immediately after ovariectomy to reach a maximum on Day 7 and there were no differences between season of ovariectomy in the initial changes in amplitude. In Exp. 2, changes in amplitude followed changes in pulse interval and there was a significant interaction between season and day of sampling. There were no significant effects of season on nadir LH concentrations which increased throughout the duration of the experiments. These results show that, in ovariectomized ewes, LH pulse frequency observed on a given day depends on time after ovariectomy, season at the time of sampling and on previous exposure of ewes to stimulatory effects of season. The direct effects of season on LH pulse frequency and seasonal changes in sensitivity to steroid feedback may contribute to control of the breeding season and their relative contributions to the beginning and end of the breeding season may differ.

Animals↗
PubMed1999

ENVIRONMENTAL AUDITING: Use of Landsat Thematic Mapper Data to Assess Seasonal Rangeland Changes in the Southeast Kalahari, Botswana.

/ Management problems arise in semiarid rangeland that are characterized by marked wet and dry seasons because of forage deficiencies in the dry season. These natural vegetation rangelands can sustain livestock all year long when forage and senesced grass are available into the dry season. Seasonal range condition data are required to provide a basis for pasture management to help locate dry season cover and thereby minimize overstocking and degradation. The generation of seasonal data using Thematic Mapper (TM) imagery was undertaken to assess changes in natural vegetation cover in the southern Botswana Kalahari. Visual analysis of spectral reflectance curves, the development of spectral separability indexes, and conventional classification analysis techniques were used to identify and differentiate rangeland features. Results from reflectance curves indicated that most rangeland cover types could be preferentially distinguished using mainly wet season data, especially on the longer TM wavebands, and that range feature differentiation was more problematic on darker soils than on lighter soils. Spectral separability indexes (SSIs) confirmed that range feature separation varied considerably as a function of waveband and was more effective in the wet than the dry season. The SSIs also showed that range feature differentiation in both seasons was most effective using a combination of the chlorophyll absorpance band (TM3) and two mid-infrared bands (TM5 and TM7). Wet season data were more effectively classified in terms of range features than dry season data although some class similarity was inferred across the two classified data sets. The work shows that overall trends may be generated by comparing seasonal data sets, thereby providing an overall basis for dry season decision making. However, particular problems arise within the dry season data sets probably because of spectral similarities between shadow and darkened vegetation cover, thereby implying that further work is needed. KEY WORDS: Semiarid rangelands; Botswana; Kalahari; Spectral differentiation; Seasonal change; Darkened vegetation cover

Journal Article↗
PubMed2001

Seasonal activation and inactivation of song motor memories in wild canaries is not reflected in neuroanatomical changes of forebrain song areas.

Seasonal, testosterone-dependent changes in sexual behaviors are common in male vertebrates. In songbirds such seasonal changes occur in a learned behavior--singing. Domesticated male canaries (Serinus canaria) appear to lose song units (syllables) after the breeding season and learn new ones until the next breeding season. Here we demonstrate in a longitudinal field study of individual, free-living nondomesticated (wild) canaries (S. canaria) a different mode of seasonal behavioral plasticity, seasonal activation, and inactivation of auditory-motor memories. The song repertoire composition of wild canaries changes seasonally: about 25% of the syllables are sung seasonally; the remainder occur year-round, despite seasonal changes in the temporal patterns of song. In the breeding season, males sing an increased number of fast frequency-modulated syllables, which are sexually attractive for females, in correlation with seasonally increased testosterone levels. About 50% of the syllables that were lost after one breeding season reappear in the following breeding season. Furthermore, some identical syllable sequences are reactivated on an annual basis. The seasonal plasticity in vocal behavior occurred despite the gross anatomical and ultrastructural stability of the forebrain song control areas HVc and RA that are involved in syllable motor control.

Animals↗
PubMed2001

An analysis of relationships among plant community phenology and seasonal metrics of Normalized Difference Vegetation Index in the northern part of the monsoon region of China.

This study focuses on relationships between the phenological growing season of plant communities and the seasonal metrics of Normalized Difference Vegetation Index (NDVI) at sample stations and pixels overlying them, and explores the procedure for determining the growing season of terrestrial vegetation at the regional scale, using threshold NDVI values obtained by surface-satellite analysis at individual stations/pixels. The cumulative frequency of phenophases has been calculated for each plant community and each year in order to determine the growing season at the three sample stations from 1982 to 1993. The precise thresholds were arbitrarily set as the dates on which the phenological cumulative frequency reached 5% and 10% (for the beginning) and 90% and 95% (for the end). The beginning and end dates of the growing season were then applied each year as time thresholds, to determine the corresponding 10-day peak greenness values from NDVI curves for 8-km2 pixels overlying the phenological stations. According to a trend analysis, a lengthening of the growing seasons and an increase of the integrated growing season NDVI have been detected in the central part of the research region. The correlation between the beginning dates of the growing season and the corresponding threshold NDVI values is very low, which indicates that the satellite-sensor-derived greenness is independent of the beginning time of the growing season of local plant communities. Other than in spring, the correlation between the end dates of the growing season and the corresponding threshold NDVI values is highly significant. The negative correlation shows that the earlier the growing season terminates, the larger the corresponding threshold NDVI value, and vice versa. In order to estimate the beginning and end dates of the growing season using the threshold NDVI values at sites without phenological data from 1982 to 1993, we calculated the spatial correlation coefficients between NDVI time-series at each sample station and other contiguous sites year by year. The results provide the spatial extrapolation area of the growing season for each sample station. Thus, we can use the threshold NDVI value obtained at one sample station/pixel for a year to determine the growing season at the extrapolation sites with a similar vegetation type for the same year.

China↗
PubMed1996

Seasonal variations of household costs of illness in Burkina Faso.

This paper assesses the seasonal variations of the time and financial costs of illness for rural households in Burkina Faso. It is based on a multiple round survey of 566 households, which included a time allocation study. The economic parameters of households which influence health seeking behavior changed substantially between the dry and rainy seasons: revenues fell in the rainy season and were exceeded by expenditures. Household production was at its peak in the rainy season resulting in significantly higher opportunity costs of time. At the same time illness perception changed: in the rainy season, significantly fewer illness episodes were perceived, and of those, the proportion perceived as severe decreased over-proportionally. Households shifted their healer choice in the rainy season away from high cost treatment, such as the hospital and dispensary, to low cost home treatment. For all these reasons, households incurred significantly fewer costs of illness in the rainy season (27% of dry season costs). Household health care expenditures were reduced to 1/6 of dry season levels, the time costs incurred by healthy household members to tend to the sick was reduced to 1/5 and the time costs of work incapacity due to sickness fell to about 1/2 of dry season levels. The authors stress the need to carry out research in all relevant seasons when studying health seeking behavior and the household costs of illness in order to avoid serious seasonal bias. They suggest policy options to increase health care utilization in the rainy season by reducing the financial and time costs of access to health care. Finally, the authors put forward a hypothesis to be tested by future research: They argue that the cognitive (changes in illness perception) and behavioral changes (different health care seeking) reflect the high opportunity costs of time and the low availability of cash households face during the rainy season. The paper discusses the negative implication that untreated illness has on the health status of household members.

Adolescent↗
PubMed2005

Variation in the relationship between anti-MSP-1(19) antibody response and age in children infected with Plasmodium falciparum during the dry and rainy seasons.

Malaria remains a major parasitic disease in Africa, with 300-500 million new infections each year. There is therefore an urgent need for the development of new effective measures, including vaccines. Plasmodium falciparum merozoite surface protein-1(19) (MSP-1(19)) is a prime candidate for a blood-stage malaria vaccine. Blood samples were collected from children aged 10 days to 15 years in the months of January-March (N = 351) and October-November (N = 369) corresponding to the dry and rainy seasons, respectively. P. falciparum infection was determined by microscopy and enzyme linked immunosorbent assay (ELISA) was used to determine the total IgG and IgG subclasses. There was a significant increase in the mean anti-MSP-1(19) antibody titre in the dry season (p < 0.05), compared to the rainy season. A significantly positive correlation between the anti-MSP-1(19) antibody titre and parasite density (p < 0.01, r = 0.138) was observed. In the rainy season, unlike in the dry season, P. falciparum positive children had higher anti-MSP-1(19) antibody titres than P. falciparum negative children and this difference was significant (p < 0.05). When all individuals were grouped together, the anti-MSP-1(19) antibody titre increased with age in both seasons (r = 0.186 and 0.002), this increase was more apparent in the dry season. However, when the study population was divided into P. falciparum positive and negative groups, it was observed that in the rainy season, there was a negative correlation between anti-MSP-1(19) titre and age in P. falciparum positive individuals, while those who were P. falciparum negative had a positive correlation between anti-MSP-1(19) titre and age. Analysis of anti-MSP-1(19) IgG subclass showed that IgG1 and IgG3 mean titres were highest in both the dry and rainy seasons with an increase in the mean antibody titres for IgG1, IgG2 and IgG3 in the rainy season. In the dry season there was a positive correlation between IgG1, IgG2, and IgG3 titres with age, while IgG4 was negative, whereas in the rainy season there was a positive correlation between IgG2 and IgG4 (non-cytophilic antibodies) with age and a negative correlation for IgG1 and IgG3 (cytophilic antibodies) with age. Seasonal differences in the level of MSP-1(19) IgG subclass titres were observed for P. falciparum negative and positive individuals. Only samples, which were positive for IgG2 and IgG4, showed positive correlation between parasitemia and total IgG. The incidence of P. falciparum infection, which increases during the rainy season, might be an important determinant of anti-MSP-1(19) antibody levels in children living in Igbo-Ora and the results point to the fact that non-cytophilic antibodies to MSP-1(19) in children might be associated with an increase in total IgG and parasitemia.

Adolescent↗
PubMed1999

Sex and seasonal differences in the rate of cell proliferation in the dentate gyrus of adult wild meadow voles.

In order to study the neurobiological basis of seasonal changes in hippocampal structure and function, the rate of cell proliferation was examined in male and female wild meadow voles captured during different seasons. We found that the number of [3H]thymidine-labeled cells varied across the seasons and across sex in the meadow vole. Non-breeding female meadow voles had a higher rate of cell proliferation and cell death than males captured during either season or breeding females. These seasonal changes in the female meadow vole were associated with both fluctuating levels of adrenal steroids and gonadal steroids. Estradiol level was highly correlated with both the number of [3H]thymidine-labeled cells and the number of pyknotic cells in female meadow voles, with high levels of estradiol being associated with low levels of cell proliferation and cell death. Corticosterone level was associated with the number of [3H]thymidine-labeled cells in the hilus of female meadow voles. This seasonal change in the number of [3H]thymidine-labeled cells was also related to the overall volume of the hippocampus. At variance with past literature, there was no statistically significant sex difference favoring males in hippocampal volume, although the means were in the predicted direction. In male meadow voles, the number of pyknotic cells was related to testosterone level, with high levels of testosterone being associated with greater levels of cell death in the granular cell layer. There was also a suggestion that the number of [3H]thymidine-labeled cells in the hilus varied seasonally in males, with higher rates of cell proliferation during the breeding season than during the non-breeding season. In summary, we found that there were large fluctuations across the season in the rate of cell proliferation in the dentate gyrus of adult female meadow voles. Females captured during the non-breeding season had higher rates of cell proliferation in the granule cell layer than females captured during the breeding season. This seasonal fluctuation was related to hormone levels, with high levels of corticosterone and estradiol being related to lower levels of cell proliferation. These seasonal changes in cell proliferation may be related to known changes in spatial learning in the meadow vole and provide insights into changes in the hippocampus that occur in other species, including primates.

Animals↗
PubMed1999

Seasonal effects on fertility and ovarian follicular growth and maturation in camels (Camelus dromedarius).

Camels are said to be seasonal breeders, but the extent to which season interferes with food supply to affect ovarian function is not fully documented. Hence, the three aims of this study were: (1) to define the breeding season of camels maintained in semi-arid conditions in southern Morocco; (2) to relate the proportion of females with active ovaries (i.e., with follicles > 5 mm), with ovulatory (11-17 mm) or cystic (> 18 mm) follicles to age and body conditions score; (3) to study the consequences of the interactions between age and body conditions score on the proportion of females ovulating and conceiving; and (4) to compare follicular maturation, using in vitro steroidogenesis by intact follicles as a marker during the transition into the breeding season (October) and peak breeding season (March). There was a clear breeding season in the two flocks studied, since over 80-90% of the matings occurred during the period from mid-November to mid-April. Collection of ovaries at slaughter (n = 238) demonstrated a significant seasonal effect on the proportion of females with active ovaries (increasing from 73.5% in October-December to 89% in January-May), but no changes in the proportion of females with ovulatory follicles. Lean females (BCS < 2.5) had a delayed initiation of ovarian function in October-December. In addition, the proportion of females with cystic follicles was also affected by season (peaking during April-May). Neither age nor body condition modulated the frequency of cysts. Finally, the proportion of females conceiving increased steadily as season progressed (peaking at 57% in April-May). Body condition score did not affect this proportion, but young females (< or = 5 years old) had a low ability to conceive. Morphological features of large follicles were unaffected by season. Ovulatory follicles contained around 10(7) granulosa and theca cells. In vitro testosterone output by intact follicles was unrelated to follicle size and season. In vitro oestradiol output increased with increasing follicle size and was larger in follicles obtained during peak breeding season than at its initiation. This may indicate that early breeding season follicles display a low aromatase activity in their granulosa cells. Whether the low oestradiol output of early breeding season follicles is resulting in the low fertility observed at this period remains to be determined.

Age Factors↗
PubMed1997

Serum levels of specific IgE, soluble interleukin-2 receptor, and soluble intercellular adhesion molecule-1 in seasonal allergic rhinitis.

BACKGROUND: There is increasing evidence that soluble interleukin-2 receptor (sIL-2R) might reflect T cell activation in vivo and soluble intercellular adhesion molecule-1 (sICAM-1) might reflect the ongoing inflammatory response in the inflamed site. OBJECTIVE: The aim of this study was to determine the effect of antihistamine tablets and allergen-specific immunotherapy on the seasonal changes in specific IgE, sIL-2R, and sICAM-1 in the serum of patients with seasonal allergic rhinitis. METHODS: This prospective study included 99 patients with seasonal allergic rhinitis due to Japanese cedar pollens and 27 nonatopic healthy volunteers. The patients were divided into an antihistamine-treated group and an immunotherapy group. Serum samples were collected before and during the pollen season from each patient to determine specific IgE, sIL-2R, and sICAM-1. RESULTS: Levels of sIL-2R before the pollen season did not differ significantly among the nonatopic group, the antihistamine-treated group, and the immunotherapy group. The levels of sICAM-1 before the pollen season were significantly higher in the antihistamine-treated group and in the immunotherapy group than in the nonatopic group. Seasonal increase in specific IgE was significant in the antihistamine-treated group regardless of their clinical outcomes. In contrast, significant increase in specific IgE was observed during the pollen season in poor responders but not in good responders to immunotherapy. Serum levels of sIL-2R and sICAM-1 were significantly increased during the pollen season in poor responders of the antihistamine-treated group and the immunotherapy group. On the other hand, neither seasonal increase in sIL-2R nor sICAM-1 was significant in good responders of the antihistamine-treated group and the immunotherapy group. CONCLUSIONS: Serum levels of sICAM-1 are higher in patients with seasonal allergic rhinitis, even outside of the pollen season when the allergen does not naturally exist. Seasonal changes in serum sICAM-1 as well as sIL-2R and specific IgE are probably objective markers to indicate the clinical efficacy of antihistamines and immunotherapy on seasonal allergic rhinitis.

Adult↗
PubMed1998

Effects of thyroidectomy and thyroxine replacement on seasonal reproduction in the red deer hind.

Two experiments were conducted to test whether thyroid hormones are required for the cessation of the breeding season in female red deer. In Expt 1, 16 mature hinds were allocated early in the breeding season (May) to the following groups: thyroidectomized (THX), thyroidectomized and treated with subcutaneous thyroxine implants which increased plasma tri-iodothyronine to physiological concentrations (THX + T4), or euthyroid controls. Plasma progesterone concentrations consistent with oestrous cyclicity were evident in all hinds during the breeding season (May-September) but after 23 September plasma progesterone concentrations became generally low (< 2.0 nmol l-1) in control and THX + T4 hinds. In contrast, thyroidectomized hinds not receiving thyroxine continued to exhibit circulating progesterone comparable with breeding season concentrations until the end of the experiment (late December). Nine hinds were ovariectomized or ovariectomized and thyroidectomized in May and treated with subcutaneous oestradiol-impregnated capsules, which were removed for periods of about 1 months during August, November and January, to test whether thyroid hormones are involved in the seasonal decline of LH secretion (Expt 2). In the presence of oestradiol, basal LH concentrations and episodic LH secretion were low during the non-breeding season (September-March) (P < 0.05). During this season, basal and GnRH-induced LH concentrations and LH pulse frequency remained similar for both groups except in the absence of oestradiol, when basal LH (3.1 +/- 0.8 versus 1.3 +/- 0.5 ng ml-1, P < 0.05 and GnRH-induced LH (25.9 +/- 3.6 versus 4.7 +/- 0.4 ng ml-1, P < 0.001) concentrations were higher in thyroidectomized hinds than in euthyroid hinds, respectively. Twenty-five hinds were ovariectomized and thyroidectomized during the breeding season and treated with subcutaneous thyroxine implants at different times to identify when thyroid hormones are required to be present to suppress LH concentrations during the non-breeding season in the absence of oestradiol. Thyroxine treatment at the beginning of or during the non-breeding season was effective in suppressing plasma LH concentration, but this action of thyroid hormones did not occur during the breeding season. These results indicate that, in red deer hinds thyroxine is required for termination of the breeding season and that thyroid gland secretions specifically block steroid-independent inhibition of reproductive activity during the non-breeding season. This inhibitory mechanism requires thyroid hormones to be present only from around the time of the end of the breeding season for their normal expression, and they remain responsive to thyroid hormones after this period.

Animals↗