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Pregnancy in a marsupial, the Tasmanian pademelon (Thylogale billardierii).

The Tasmanian pademelon, Thylogale billardierii, is a medium-sized wallaby that adapts well to captivity and, unlike the well-studied tammar wallaby, is capable of breeding all year round. It may, therefore, be a useful model species for research into the reproductive biology of macropod marsupials. This paper presents necessary background data on histological changes in the reproductive organs and the rate of embryonic growth during gestation in T1 billardierii. After Day 4 RPY (removal of young from the pouch) the gravid and non-gravid uteri differ significantly in some histological parameters. The corpus luteum becomes active by Day 6 RPY and is fully developed by Day 14 RPY; it begins to degenerate from Day 19 RPY. Plasma progesterone concentrations through gestation follow a pattern similar to that in the tammar wallaby. There is an early, smaller, peak at Day 5 RPY, with plasma concentrations of progesterone then falling until the larger pre-partum peak occurs several days before birth.

Animals↗

The gene encoding multidrug resistance is induced and expressed at high levels during pregnancy in the secretory epithelium of the uterus.

A survey of the expression of the multidrug-resistance gene (mdr) in mouse tissues revealed that a mdr mRNA species is expressed at extremely high levels in the gravid uterus. mdr mRNA expression levels increase dramatically during pregnancy compared to the relatively low levels of expression observed in the nongravid uterus. In situ hybridization experiments revealed that the increased expression of the mdr mRNA is specifically localized to the secretory epithelial cells of the endometrium. Immunocytochemistry studies with a mdr glycoprotein-specific antiserum demonstrate that the mdr glycoprotein is predominantly localized to the luminal surface of the secretory epithelial cells. These results indicate that the mdr gene expression in the uterus is controlled by the physiologic changes associated with pregnancy. Our data are consistent with a potential role for the mdr glycoprotein in the transport of substrate across the secretory epithelium of the gravid uterus.

Animals↗

Stable genetic transformation of a beneficial arthropod, Metaseiulus occidentalis (Acari: Phytoseiidae), by a microinjection technique.

A microinjection technique has resulted in stable transformation of the western predatory mite Metaseiulus occidentalis. Early preblastoderm eggs within gravid females were microinjected. The needle was inserted through the cuticle of gravid females into the egg, or the tissue immediately surrounding the egg. This maternal injection method resulted in relatively high levels of survival and transformation. Transformation was achieved without the aid of any transposase-producing helper plasmid. The predatory mite was transformed with a plasmid containing the Escherichia coli beta-galactosidase gene (lacZ) regulated by the Drosophila hsp70 heat-shock promoter. Putatively transformed lines were isolated based on beta-galactosidase activity in first-generation larvae. Transformation was confirmed in the sixth generation by polymerase chain reaction amplification of a region spanning the Drosophila/E. coli sequences. Amplification of a nested region, also spanning the interspecific boundary, provided further evidence for stable transformation. Maternal microinjection may be adaptable to other beneficial arthropods, particularly other phytoseiid mites. Genetic transformation of M. occidentalis may improve its efficiency as a biological control agent as well as provide a method for investigating details of its physiology and ecology.

Animals↗

Seasonal dynamics of Proteocephalus sagittus in the stone loach Barbatula barbatula from the Hana River, Czech Republic.

The seasonal cycle of the cestode Proteocephalus sagittus (Cestoda: Proteocephalidae) was studied for the first time in the stone loach Barbatula barbatula from the Hana River, Czech Republic. A total of 180 loaches were examined monthly from January to December 2001. The parasite occurred in loaches throughout the year but infection parameters differed significantly among seasons, with the highest values of prevalence and abundance from the late winter to the early summer. Parasite recruitment took place in the winter and early spring and the worms sexually matured in the late spring and early summer. In contrast to P. torulosus, the gravid worms of which laid eggs only at the end of the spring/beginning of the summer, gravid worms of P. sagittus were also found, although in low numbers, in the autumn and early winter. The rate of infection of loach with P. sagittus was neither dependent on the sex nor on the size of its fish host.

Animals↗

Population and seasonal distribution of Procamallanus daccai in Eutropiichthys vacha in Kaptai Lake, Chittagong, Bangladesh.

The population and seasonal distribution of Procamallanus daccai (Nematoda: Procamallanidae) in Eutropiichthys vacha (Siluridae) from the Kaptai Lake were studied for a period of 20 months during 1986-1987. A total of 208 fish were necropsied and 5652 worms were recovered, of which 2392 were from 87 infected male fish and 3260 were from 89 infected female fish. Prevalence values varied from 50% to 95%. The intensity and abundance of nematodes fluctuated over the study period and are statistically significant (F=14.87, P<0.0001), and showed a seasonal preference for the summer period (F=33.39, P<0.05). The mean intensity was the highest in the smallest size group at 66.3+/-12.7 which gradually decreased to 4+/-1.89 in the largest size group. No significant differences were found between parasites from male and female hosts, except in the summer. Male parasites were less abundant in the population. Female worms were grouped into immature, maturing and gravid and all these stages were present throughout the year. The highest occurrence of both immature and gravid P. daccai was found during the months of February to April each year. Peak recruitment seems to occur during this period due to the presence of high quantities of immature worms.

Animals↗

Light trap collections of ovipositing Simulium squamosum in Ghana.

At a site near Boti waterfalls in southern Ghana a total of 14 644 female and two male Simulium squamosum were caught in four nights in Monks Wood light traps. The highest catch, of 6520 females, was obtained in a single night with an ultraviolet light tube that had a one-second flash rate. About 12% of the females caught were gravid and dissections of non-gravids showed that they had oviposited very recently. The traps were clearly catching females before or soon after oviposition. The same traps caught none or very few blackflies when placed in two other localities near Akosombo. Trap location appeared very important in sampling ovipositing females of S. squamosum.

Animals↗

Studies on oviposition characteristics of Mansonia (Mansonioides) mosquitoes in southern Thailand.

Oviposition characteristics of Mansonia (Mansonioides) mosquitoes were studied to assess future possibilities for their control. Special emphasis was given to the study of the factors, especially the host plant species, which guide the gravid females towards the oviposition site. Initially, egg dispersal throughout the breeding place was assessed by comparing egg densities between so-called areas of 100-200 m2, each characterized by reasonable homogeneity in its flora. Some of these areas were preferred by gravid females, indicating an aggregative type of distribution. There was no evidence that the attractiveness of areas was correlated with the availability of preferred host plants. Egg dispersal within areas was then studied using randomly chosen plots of 1 X 1 m or 15 X 15 cm as sampling units. This again revealed aggregative egg distributions which could be fitted to a negative binomial expectation. The amount of visible water surface, rather than the availability of host plants, appeared to determine the attractiveness of the plots. The dispersal within 1 m2 experimental plots containing the host plants Pistia, Eichhornia and Salvinia was then investigated and this showed clearly that specific levels of attractiveness of plant species influenced egg dispersal. These levels were modified by (i) the presence of grasses in the immediate surroundings, (ii) features of grass growth and (iii) the type of host plant arrangement. It was concluded that the factors responsible for egg aggregations vary with the size of the samples compared, and that the host plant species plays a significant role only for the distribution within quite small units of the breeding place.

Animals↗

The epidemiology of Echinococcus granulosus in Great Britain. V. The status of subspecies of Echinococcus granulosus in Great Britain.

Twenty-five years ago Williams and Sweatman suggested that in Great Britain there are two subspecies of Echinococcus granulosus--E. granulosus granulosus and E. granulosus equinus. Echinococcus granulosus granulosus does not mature either in foxes or in horses: E. granulosus equinus will mature in either. The prepatent period of E. granulosus granulosus in the definitive host is about 42 days while that of E. granulosus equinus is about 70 days. Each subspecies has a characteristic morphology. More recently, in the course of seven experiments, dogs, red foxes (Vulpes vulpes crucigera), arctic foxes (Alopex lagopus), badgers (Meles meles), domestic ferrets and domestic cats have been infected with protoscoleces derived from hydatid cysts of human, equine and ovine hosts from different regions of England and Wales. Transmissions to horses and sheep were always succeeded by the development of viable hydatid cysts; transmissions to dogs and foxes, by the development of gravid adults. The prepatent period in both dogs and foxes was invariably about 70 days (or longer) and the morphology of all the adult parasites in these definitive hosts was characteristic of E. granulosus equinus. All the evidence derived from these experiments supports the view that there is, in Great Britain, but one subspecies of E. granulosus. That one subspecies is E. granulosus equinus. It infects dogs, red foxes, arctic foxes (experimentally), cats (experimentally), humans, sheep, goats, horses, donkeys, pigs, cattle, roe deer and reindeer (in Scotland). Attempts to transmit E. granulosus to badgers and domestic ferrets were unsuccessful. Of 123 cats infected with protoscoleces of horse origin, one gravid adult parasite was recovered from one animal.

Animals↗

The growth and development of Echinococcus granulosus of sheep origin in dogs and foxes in Britain.

Four separate experiments were carried out by dosing dogs (Beagles and Border collies) and red foxes with protoscoleces obtained from hydatid cysts in sheep from mid-Wales. The dogs and foxes were killed at intervals over a period from 34-180 days after infection and the intestines were examined for Echinococcus granulosus. Border collie dogs were efficient hosts in that large numbers of worms developed, with gravid segments present by 55 days after infection; but Beagle dogs were poor hosts in that only small numbers of immature worms developed. Foxes were poor hosts in that few or no worms developed, but gravid segments were seen in three of 29 foxes. The worms showed morphological features similar to the 'sheep' rather than the 'horse' strain.

Animals↗

The epidemiology of Echinococcus granulosus in the U.K. VIII. The structure of adult colonies of E.g. equinus say in farm dogs in Wales.

The status of Echinococcus granulosus equinus in farm dogs was examined in two valleys in South Powys, Wales. In one valley 76% of the dogs examined were infected, and there was at least one infected dog on every farm except one. In the second valley 49% of the dogs were infected. The structure of natural adult colonies of Echinococcus is described, and the population dynamics of the parasite in the U.K. is discussed. Every colony in the dogs, excepting the very smallest and the very youngest, consists of parasites at several stages of development. Most colonies comprise less than 20 worms. Colony density is greatest about the second or third eighth of the total length of the small intestine. The general characteristics of a colony (other than number) are reflected in the characteristics of the group of worms 'resident' in each successive eighth of the small intestine. Neither the age nor the sex of the host has any obvious effect on the incidence or the size of the colony, its development, or the ultimate infectivity of the colony. The parasites continue to grow throughout life, and growth may be largely independent of the worms' development. As a result, their length is very variable. The number of eggs in each gravid proglottid varies considerably, from 12-1626. All the evidence available and derived from the study of natural populations confirms that E. granulosus is an obligate self-fertilizing hermaphrodite, and that serial development of gravid proglottids does not occur.

Animals↗

Developmental toxicity of sarin in rats and rabbits.

Sarin (Agent GB, isopropyl methylphosphonofluoridate) is an organophosphate cholinesterase inhibitor. Sarin (Type I or Type II) was administered by gavage to CD rats on d 6-15 of gestation at dose levels of 0, 100, 240, or 380 micrograms/kg/d and to New Zealand White (NZW) rabbits on d 6-19 of gestation at dose levels of 0, 5, 10, or 15 micrograms/kg/d. Females were weighed on gestational days (GD) 0, 6-16 for rats and 6-20 for rabbits, and immediately prior to termination (GD 20 for rats and GD 29 for rabbits). All animals were monitored daily for clinical signs of toxicity throughout dosing and until sacrifice. At necropsy, gravid uteri were weighed and examined for the number and status of implants (live, resorbed, or dead). Individual fetal body weight, malformations, and variations (external, visceral, and skeletal) were recorded. Rat and rabbit dams in the high-dose groups exhibited significant signs of maternal toxicity and increased maternal mortality. Examination of gravid uteri revealed no statistical differences among treatment groups in the incidence of resorptions or of dead or malformed fetuses, or in average body weight of live fetuses per litter. These results show no evidence or developmental toxicity in the CD rat or NZW rabbit following exposure to either Type I or Type II sarin during embryonic differentiation and major organogenesis, even at a dose that produced maternal toxicity.

Administration, Oral↗

Cholinesterase activity in Thysaniezia giardi (Cestoda, Anoplocephalidae).

The activity of cholinesterase was determined separately in the mature and gravid proglottids of Thysaniezia giardi and its significance is discussed. The mean values of the enzyme in mature and gravid proglottids were respectively 225.60 +/- 28.55 and 75.00 +/- 11.64 units per gram of wet weight.

Animals↗

Oral (drinking water) developmental toxicity studies of bromodichloromethane (BDCM) in rats and rabbits.

Crl:CD(SD)IGS BR VAF/Plus (Crl SD) rats and Hra(NZW) SPF rabbits were tested for potential developmental toxicity from bromodichloromethane (BDCM) provided continuously in the drinking water during gestation (gestation days [GDs] 6 to 21 in rats and GDs 6 to 29 in rabbits). Concentrations of 0, 50, 150, 450, or 900 ppm of BDCM were used for rats; 0, 15, 150, 450, or 900 ppm were used for rabbits (in dose range-finding studies, 1350 ppm was excessively maternotoxic to both species). Investigated maternal parameters included viability, clinical signs, water and feed consumption, and body weights. Maternal gross lesions, gravid uterine weights, abnormal placentas, and numbers of corpora lutea, implantation sites, live and dead fetuses, and early and late resorptions were observed at time of Caesarean sectioning (GD 21 in rats; GD 29 in rabbits). Body weights, sex ratios, and morphological abnormalities (external, soft tissue, and skeletal) were noted in the fetuses. Mean consumed doses of BDCM were calculated to be 0, 2.2, 18.4, 45.0, or 82.0 mg/kg/day for the rats, and 0, 1.4, 13.4, 35.6, or 55.3 mg/kg/day for the rabbits (approximate human intake is 0.8 microg/kg/day [0.0008 mg/kg/day] in adults). In pregnant rats, toxicologically important, statistically significant effects included reduced absolute (g/day) and relative (g/kg/day) water consumption values at > or =50 ppm (2.2 mg/kg/day) and reduced body weight gains (also when corrected for gravid uterine weight) and absolute (g/day) and relative (g/kg/day) feed consumption values at >450 ppm (45.0 mg/kg/day). These parameters were also significantly reduced at > or =450 ppm (35.6 mg/kg/day) in pregnant rabbits (significant weight loss occurred in the rabbits at 900 ppm, i.e., 55.3 mg/kg/day). Thus, the maternal no-observable-adverse-effect level (NOAEL) for BDCM was 150 ppm, i.e., 18.4 and 13.4 mg/kg/day in rats and rabbits, respectively. No adverse effects on embryofetal viability, growth, sex ratio, gross external, soft tissue, or skeletal morphology occurred at 900 ppm in rats or rabbits. Minimal delays in the ossification of forepaw phalanges and hindpaw metatarsals and phalanges occurred in rat fetuses at 900 ppm; delays were considered marginal, reversible, and associated with severely reduced maternal weight gain. Therefore, the developmental NOAEL for rats was 450 ppm (45.0 mg/kg/day), whereas in rabbits it was 900 ppm (55.3 mg/kg/day). These NOAELs are 56,250 and 69,120 times the human adult exposure level of 0.0008 mg/kg/day, respectively. Based on the results of these studies, BDCM should not be identified as a risk to development of human conceptuses.

Administration, Oral↗

[Fe-, Cu-, Zn-, Ni- and Mn-concentrations in sow's milk during a five-week lactation period].

In a trial with 18 sows of the German landrace in three groups the dietary copper supply was varied in gravidity and lactation. Iron, copper, zinc, nickel and manganese concentration of milk was measured on 11 different days during the five weeks' lactation period in response to alimentary copper supply. Copper supply did not influence iron, zinc, and manganese concentration even if it was deficient during gravidity and lactation. Mature sow's milk contained 1.2 micrograms Fe, 1.5 micrograms Cu, 6-8 micrograms Zn, 0.16-0.23 microgram Ni and 0.07-0.13 microgram Mn per g fresh milk. First colostrum contained higher copper and zinc concentrations and lower concentrations of nickel and manganese compared to mature milk. Fe concentration remained constant. This investigation reproduced and completed thereby previous results. It was concluded that in copper deficiency status the interactions of copper with iron, zinc, nickel and manganese may not be effective for the excretion pathway milk.

Animals↗

[Energy requirement of young female cattle. 3. Reproduction and products of conception].

The results with regard to reproduction obtained from a study lasting several years of the energy requirement of young female cattle reared with different intensity are described. It becomes apparent that there are relations between feeding, rearing intensity and insemination expenditure. Age and weight at the time of conception in the individual test series averaged between 290 and 630 days and 270 and 430 kg respectively. The weight of the conceptional products of 31 calvings was registered and, according to Jakobsen (1956, 1957), the energy and N content of the conceptional products was proportionally assigned to the prenatal test periods. In the last 140 days of gravidity the N balance per animal and day increases from 16 to 23 g. N retention of the cows is low in the last days of gravidity. The utilization of metabolizable energy for the development of conceptional products is calculated as a conventional comparative value provided the maintenance requirement per unit metabolic body weight of the cows and the utilization of metabolizable energy for energy retention in the cows on an average of 156 individual values of 12 +/- 8% are the same and correspond in their magnitude to analogous findings of other authors, mainly compiled from dairy cows.

Animals↗

Fetotoxicity and teratogenesis of SWL treatment in the rabbit.

The potential effects of extracorporeal application of shockwaves on an embryo or fetus were explored in an animal model. In experimental Series A, the fetuses of 30 gravid rabbits were exposed to piezoelectrically induced and sonographically guided shockwaves on Day 25 or 20 of gestation under technical conditions corresponding to extracorporeal lithotripsy in humans. Fetotoxicity was examined by abdominal section 24 hours or 9 days later, and immediate/intermediate damage was assessed (resorptions, viability, gross injuries, and microscopic lesions of the target and neighboring fetuses). In series B, the kidneys of an additional 28 gravid rabbits (including a control group) were exposed to the same shockwave treatment on Day 11 of gestation in order to investigate indirect embryotoxic effects, including teratogenic potency. One day before the expected birth, the maternal kidneys, uteri, and adjacent organs were examined for lesions, and the 156 offspring were assessed for embryolethal, embryonoxious, or teratogenic sequelae. Shockwave targeting of the cranium, thorax, abdomen, or placenta was usually lethal to the fetuses. When the uterine wall or the space between two fetuses was targeted, the fetuses suffered from superficial hematoma, as was found in the surrounding soft tissues within a radius of 1.5 cm. Fetuses outside this region were vital and free of lesions. Shockwave treatment of the maternal kidney resulted in renal petechial hemorrhage or subcapsular hematoma. However, statistically significant embryotoxic or teratogenetic effects could be demonstrated neither from maternal data (resorptions) nor from fetal findings (body measurements, vitality test, inner organs, skeletal deformities). When using a piezoelectric lithotripter with a small focus of high energy, lesions of a fetus are to be expected only when it is located in or close to the focus. It seems that embryotoxic or teratogenic sequelae do not occur when shockwaves are focused outside the uterus. Nonetheless, this preliminary research does not justify clinical use of extracorporeal shockwave lithotripsy in pregnant humans.

Abnormalities, Multiple↗

HIV and other predictors of serum folate, serum ferritin, and hemoglobin in pregnancy: a cross-sectional study in Zimbabwe.

BACKGROUND: Folate and iron status and hemoglobin concentrations are important to maternal and infant health. OBJECTIVE: Our goal was to identify predictors of serum folate, serum ferritin, and hemoglobin. DESIGN: This was a cross-sectional study of 1669 pregnant women (22-35 wk of gestation) in Harare, Zimbabwe, who were receiving prenatal care. The statistical effects of age, season, gestational age, gravidity, HIV-1 infection, malaria parasitemia, and serum alpha1-antichymotrypsin (ACT) on serum folate, serum ferritin (log10 transformed), and hemoglobin were estimated by using multiple linear regression analyses. RESULTS: Serum folate (x: 11.4 micromol/L) was 0.52-nmol/L (95% CI: 0.04, 1.0) lower in HIV-infected women than in uninfected women and 0.65-nmol/L (0.014, 1.28) lower in weeks 25-35 than in weeks 22-25. Serum ferritin (geometric x: 11.6 microg/L) was 0.93 times (0.86, 0.99) lower in HIV-infected women and 2.25 times (1.41, 3.61) higher in women with malaria parasitemia than in uninfected women. Similarly, serum ferritin was 0.71 times (0.63, 0.79) higher in weeks 32-35 than in weeks 22-25 and 1.21 times (1.12, 1.29) higher in gravida > or =3 than in gravida 1. Elevated serum ACT was a strong predictor of serum folate, serum ferritin, and hemoglobin. HIV infection was associated with a 12.9-g/L (8.9, 16.8) lower hemoglobin concentration in women with nondepleted iron stores but low serum retinol and a 7-8-g/L lower hemoglobin concentration in women with other combinations of serum ferritin and retinol (P for interaction = 0.038). Season, age, gestational age, and gravidity were not significant predictors of hemoglobin. Low serum folate, ferritin, and retinol were associated with low hemoglobin. CONCLUSIONS: HIV was associated with lower serum folate, serum ferritin, and hemoglobin. HIV infection was also associated with lower hemoglobin, particularly in women with stored iron and low serum retinol. Low serum folate, ferritin, and retinol were associated with low hemoglobin.

Acute-Phase Reaction↗

Utero-ovarian interactions during early pregnancy: role of conceptus-induced vasodilation.

Recent studies of utero-ovarian blood flow have indicated an interaction between the gravid uterus and the ovary in maintaining luteal function during early pregnancy. On days critical for the continuation of pregnancy, blood flow to the corpus luteum (CL) increases several-fold, coincident with an increase in concentrations of progesterone (P4) in systemic blood. Enhanced ovarian secretion of P4 may amplify the vasodilatory "signal" of the conceptus and thus ensure an adequate uterine blood supply to support early fetal growth. Utero-ovarian vasodilation during early pregnancy may not only stimulate luteal function directly but also enhance transport of luteotropic substances to the ovary. Possible candidates for the vasodilatory factor(s) secreted from the early gravid uterus include estrogens and prostaglandins (PG) E. In addition, conversion of estrogens to their catechol forms, which have both vasodilatory and luteotropic activities, may be important for the successful establishment of pregnancy.

Animals↗