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PubMed1998

Improvement of ram sperm cryopreservation protocols assessed by sperm quality parameters and heterogeneity analysis.

Semen cryopreservation processes generally decrease sperm quality and fertility rate, but this is highly dependent on the specific susceptibility of sperm cells to low temperatures. In order to study the effect of cooling, freezing, and thawing on ram spermatozoa, sperm viability (plasma membrane integrity), HOS test (hyposmotic swelling test), and individual motility were assessed in fresh, cooled, and frozen-thawed samples. The cryoprotective ability of four extenders [Triladyl-yolk (20% Triladyl, 20% egg yolk), Salamon (9.9% raffinose, 2% sodium citrate, 15% egg yolk, 5% glycerol), I.N. I.A. (6.31% Tes, 1.51% Tris, 6% egg yolk, 3% glycerol), and Fiser (F1: 3.25% Tris, 9.3% fructose, 1.7% citric acid, 25% egg yolk, 2% glycerol; F2: 0.68% sodium citrate, 0.15% TES, 0.36% glycine, 10.18% lactose, 1.18% raffinose, 0.5% fructose, 3.95% dextran (150,000-200, 000 MW); 12% of the obtained solution was replaced by the same volume of glycerol)] was tested, as well as the effect of adding various compounds (bovine lactalbumin and serum albumin, vitamin E, dithiothreitol, bull seminal plasma, glycine betaine, proline, phosphatidylcholine, and cholesterol) to Fiser's medium. Simultaneously, centrifugal counter-current distribution in an aqueous two-phase system was carried out to analyze the effect of the four extenders on sperm surface heterogeneity. The results showed that ram spermatozoa undergo a dramatic loss of heterogeneity, viability, motility, and positive response to the HOS test during freezing and thawing. These changes were partially prevented by diluting samples in Fiser's extender containing egg yolk and glycerol. A considerable increase in sperm quality with respect to that obtained in Fiser's control sample was achieved by the addition of bovine lactalbumin, vitamin E, bovine serum albumin, and bovine and ram seminal plasma.

Animals↗
PubMed2001

[Organochlorine residues in eggs of night heron breeding in Yuantouzhu, Wuxi and their functions as bioindicator].

This study analyzed chlorinated pesticides in eggs of night heron breeding in Yuantouzhu, Tai lake. The HCH isomers, DDT, DDD, DDE, endrine and heptachlor epoxide were detected out in egg samples. The residue level and the percent of detection of beta-HCH and p,p'-DDE were significantly high. The mean value of p,p'-DDE was 0.906 microgram/g dry weight. Most of the chlorinated pesticides in samples from Wuxi were higher than those of Gongqing city, Jiangxi province. Oppositely, the hatching rate of night heron egg in Wuxi region was lower than that in Gongqing city. It may be related to the difference of DDE residual levels. Using organochlorine residue in eggs of water-fowls as an indicator for environmental quality assessment is feasible.

Animals↗
PubMed2000

Sexual selection and the evolution of exclusive paternal care in arthropods.

Internal fertilization and anisogamy are thought to impede the evolution of exclusive paternal care by reducing paternity assurance and increasing male promiscuity. The potential role of sexual selection in easing these constraints is currently being examined in vertebrates but has not been seriously studied in most arthropods. To distinguish the effects of sexual from natural selection on the evolution of arthropod paternal care, I tested predictions of the state of several life history and behavioural traits under both forms of selection across all known taxa with exclusive paternal care. The results suggest parallels between prezygotic nuptial gifts and exclusive postzygotic paternal care and support the hypothesis that, in arthropods, male behaviours that enhance female reproductive success either directly by releasing females from the fecundity constraints of maternal care (enhanced fecundity hypothesis) or indirectly by identifying mates with superior genes (handicap principle) are traits on which sexual selection has acted. Under such conditions males willing to guard young become preferred mates for gravid females and enjoy greater promiscuity than males unable or unwilling to guard. Females use nest construction or the act of guarding another female's eggs as honest signals of paternal intent and quality. Copyright 2000 The Association for the Study of Animal Behaviour.

Journal Article↗
PubMed1997

The effect of Plasmodium yoelii nigeriensis infection on ovarian protein accumulation by Anopheles stephensi.

Both anopheline and culicine mosquitoes have been shown to incur a reduction in reproductive fitness when infected with malaria parasites. The agent of rodent malaria, Plasmodium yoelii nigeriensis, was used as a laboratory model to investigate changes in the accumulation of protein in the ovaries of Anopheles stephensi when infected with oocysts or when feeding on mice with heavy asexual parasitaemia but no mature gametocytes. Herein we report that during the early phases of the gonotrophic cycle the ovarian protein content increased normally; however, after 16 h post-blood-feeding there was a significant reduction in the total protein content in ovaries from infected mosquitoes. The development of ovaries from mosquitoes undergoing a second gonotrophic cycle and containing maturing oocysts was similarly affected. Ovarian protein profiles produced by sodium dodecyl sulfate-polyacrylamide gel electrophoresis showed a depletion of the yolk protein vitellin. Ovaries from mosquitoes feeding on a mouse with 31% parasitaemia, no detectable gametocytes and a low haematocrit (29% packed cell volume) also exhibited a reduction in protein content, although this did not occur until much later in the gonotrophic cycle. The role of blood-meal quality and malaria infection in the reduction in egg production is discussed.

Animals↗
PubMed2003

Seasonal shift from bottom-up to top-down impact in phytophagous insect populations.

Although many studies now examine how multiple factors influence the dynamics of herbivore populations, few studies explicitly attempt to document where and when each is important and how they vary and interact. In fact, how temporal variation in top-down (natural enemies) and bottom-up (host plant resources) factors affect herbivore dynamics has been suggested as a particularly important yet poorly understood feature of terrestrial food webs. In this study we examined how temporal changes in predator density (wolf spiders, sheet-web builders, and mirid egg predators) and host-plant resources (plant quality and structural complexity) influence the population dynamics of the dominant phytophagous insects on Atlantic-coast salt marshes, namely Prokelisia planthoppers (Homoptera: Delphacidae). We designed a factorial experiment in meadows of Spartina alterniflora to mimic natural variation in vegetation quality and structure by establishing two levels of plant nutrition (leaf nitrogen content) by fertilization, and two levels of habitat complexity by adding leaf litter (thatch). We then assessed seasonal changes in the strength of bottom-up (plant quality) and top-down (predator) impacts on planthopper populations. Planthopper populations responded positively to increased plant quality treatments in late summer. Despite the greater number of planthopper adults colonizing fertilized Spartina plots compared to unfertilized controls, the offspring of these colonists were much less abundant at the end of the season in fertilized plots, particularly those with thatch. The initial colonization effect was later erased because arthropod predators selectively accumulated in fertilized plots where they inflicted significant mortality on all stages of planthoppers. Predators rapidly colonized fertilized plots and reached high densities well in advance of planthopper colonization, a response we attribute to their rapid aggregation in complex-structured habitats with readily available alternative prey. Our results suggest that plant resources not only mediate the strength of predator impacts on herbivore populations, but they also promote the coupling of predator and prey populations and thus influence when enemy impacts are realized.

Animals↗
PubMed1989

In vitro fertilization of bovine follicular oocytes recovered by laparoscopy.

Thirty-three laparoscopies were performed on 16 follicle stimulating hormone (FSH)-superovulated cows (one to four laparoscopies per cow). Two hundred and four follicles were aspirated (6.18/cow) and 157 oocytes (77% recovery rate) were isolated. Sixty percent of the oocytes found were considered to be of good to excellent quality. In cows with ongoing ovulations at laparoscopy only 32% of the oocytes were suitable for fertilization. Twenty-four percent of the oocytes from cows with no ovulation and 16% from cows with ovulations were fertilized. Higher proportions of oocytes were fertilized in cows showing estrous behavior vs cows with no signs of estrus (25 vs 15%). Using lysolecithin-treated spermatozoa, 28% of the oocytes with good to excellent quality were fertilized, and 35% of the fertilized eggs cleaved in vitro to two- to four-cell stages.

Journal Article↗
PubMed1997

A review on disease transmission studies in relationship to production of embryos by in vitro fertilization and to related new reproductive technologies.

This paper addresses the circumstances of germplasm contamination and updates on transmission of pathogenic agents by embryos produced in vitro and by associated techniques. It has been shown that some pathogenic agents might have been associated with the follicular oocytes and oviductal cells, collected for in vitro fertilization (IVF), resulting in infected embryos. Experimental introduction of pathogenic agent with oocytes or infected semen into the IVF system allows, in most cases, for the fertilization of eggs and for the production of some transferable quality embryos. Rendering of oocytes and embryos free of infectious pathogens, using the standard sequential washing or enzymatic treatment, is inconsistent and more difficult in the presently used in vitro fertilization system as compared to in vivo produced embryos.

Journal Article↗
PubMed2003

Rapid confirmatory assay for determining 12 sulfonamide antimicrobials in milk and eggs by matrix solid-phase dispersion and liquid chromatography-mass spectrometry.

A rapid confirmatory method for determining 12 sulfonamide (SAs) antibacterials in whole milk and eggs is presented. This method is based on the matrix solid-phase dispersion technique with hot water as extractant followed by liquid chromatography (LC)-mass spectrometry (MS). The LC-MS instrument was equipped with an electrospray ion source and a single quadrupole. After 4 mL of a milk sample containing the analytes had been deposited on sand (crystobalite), this material was packed into an extraction cell. SAs were extracted by flowing 4 mL of water through the cell heated at 75 degrees C. With some modifications, this procedure was applied also to eggs. After pH adjustment and filtration, 0.5 mL of the final extracts was then injected into the LC column. MS data acquisition was performed in the positive-ion mode and by monitoring at least three ions for each target compound. The in-source collision-induced dissociation process produced confirmatory ions. At the 50 ng/g level, recovery of the analytes in milk and eggs was 77-92% with relative standard deviations ranging between 1 and 11%. Estimated limits of quantification (S/N = 10) were 1-3 ng/g of SAs in milk and 2-6 ng/g in eggs. With both matrices, attempts to reduce the analysis time by using a short chromatographic run time caused severe ion signal suppression for the early-eluted SAs. This effect was traced to competition effects by polar endogenous coextractives, maybe proteinaceous species, which are eluted in the first part of the chromatographic run. This unwelcome effect was almost completely removed by simply adopting more selective chromatographic conditions.

Animals↗
PubMed2001

Hypothalamic-pituitary suppression with oral contraceptive pills does not improve outcome in poor responder patients undergoing in vitro fertilization-embryo transfer cycles.

PURPOSE: To evaluate and compare the use of OCP with GnRHa for hypothalamic-pituitary suppression in poor responder IVF patients. METHODS: Retrospective analysis of IVF-ET cycles of poor responders. Hypothalamic-pituitary suppression with OCP (Group I, n = 29) or GnRHa (Group II, n = 52), followed by stimulation with gonadotropin, oocyte retrieval, and embryo transfer. Baseline characteristics and cycle outcomes were compared. RESULTS: 73 women underwent 81 cycles from 1/1/1999 to 1/1/2000. Baseline characteristics were similar. 31/81 (38%) cycles were cancelled (Group I, 14/29 (48%) vs. Group II, 17/52 (33%), NS). Cycle outcomes including amount of gonadotropin, number of eggs retrieved, number of embryos transferred, and embryo quality were similar. Patients in Group I required fewer days of stimulation to reach oocyte retrieval. Pregnancy outcomes were similar in the two groups. CONCLUSION: Our retrospective analysis revealed no improvement in IVF cycle outcomes in poor responders who received OCPs to achieve hypothalamic-pituitary suppression instead of GnRHa.

Adult↗
PubMed1998

In-vitro human spermatozoa nuclear decondensation assessed by flow cytometry.

The process of sperm chromatin decondensation occurs when a spermatozoon enters an ovum. Protamine disulphide bonds are reduced to SH and the polycationic protamines combine with the polyanionic egg protein, nucleoplasmin, thus being stripped from DNA which then combines with histones. Defective chromatin decondensation will thus prevent further development of the male pronucleus. In this study human sperm samples were incubated in vitro at 28 degrees C (using a medium in which the polyanion, heparin, substitutes for nucleoplasmin and beta-mercaptoethanol for egg glutathione) for 10, 20 and 30 min before stopping the reaction with formalin (to 3.6%). The DNA of the fixed cells was stained with Acridine Orange by a one-step method and subjected to flow cytometry and data analysis, in which a zone characteristic of condensed chromatin is outlined on red-green fluorescence contour plots. After 20 min of incubation 97% of the control spermatozoa that were in the mature window (WIN M) had decondensed and moved out of this region. Defects in sperm decondensation were seen in four semen samples of the 20 that were tested. In cases where spermatozoa fail to produce a fertilized egg the cause may lie with defective chromatin quality, including failure of the sperm chromatin to decondense. The method described here is a simple procedure for detecting sperm samples containing such defective cells.

Animals↗
PubMed1998

Broiler industry strategies for control of respiratory and enteric diseases.

The commercial broiler industry is a modern day agricultural success due to popular consumer demand, healthy flocks, and least cost production. Preventive medicine is the key for economical control of disease in integrated broiler companies, and includes quarantine-eradication, controlled-exposure, and preventive feed medication. Respiratory and enteric diseases present a continuing, potential threat for economic loss. Most exotic and egg-transmitted poultry diseases have been controlled by reduction or eradication policies. Endemic diseases are controlled by mass vaccination and preventive feed medication. Improvements in genetics, housing, equipment, and disease surveillance has allowed continued improvements in disease prevention. Attention to detail and management of risk is crucial to industry success. With fast industry growth and market maturity of the broiler industry, new challenges have risen. These challenges include increased poultry house density, increasing economic pressures, changing industry attitudes, and increased governmental regulations that will strain the continued success of today's control strategies.

Animal Husbandry↗
PubMed2002

Sex matters in meiosis.

In mammals, fertilization typically involves the ovulation of one or a few eggs at one end of the female reproductive tract and the entry of millions of sperm at the other. Given this disparity in numbers, it might be expected that the more precious commodity-eggs-would be subject to more stringent quality-control mechanisms. However, information from engineered mutations of meiotic genes suggests just the opposite. Specifically, the available mutants demonstrate striking sexual dimorphism in response to meiotic disruption; for example, faced with adversity, male meiosis grinds to a halt, whereas female meiosis soldiers on. This female "robustness" comes with a cost, however, because aneuploidy appears to be increased in the resultant oocytes.

Aneuploidy↗
PubMed2001

Evolution of exclusive paternal care in arthopods.

Exclusive male care of offspring is the rarest form of postzygotic parental care among animals and has arisen independently in only 13 arthropod taxa. To distinguish the effects of sexual selection from those of natural selection on the evolution of arthropod paternal care, predictions concerning several life-history and behavioral traits resulting from both forms of selection are made and tested across all known taxa with exclusive paternal care. Comparisons suggest parallels between prezygotic nuptial gifts and exclusive postzygotic male care and support the hypothesis that, in arthropods, male behaviors that enhance female reproductive success either directly, by releasing females from the fecundity constraints of maternal care (enhanced fecundity hypothesis), or indirectly, by identifying mates with superior genes (handicap principle), are traits on which sexual selection has acted. Under such conditions, males that are willing to guard young become preferred mates for gravid females and enjoy greater promiscuity than males that are unable or unwilling to guard. Females use nest construction or the act of guarding another female's eggs as honest signals of paternal intent and quality.

Animals↗
PubMed1995

Age-acquired resistance and predisposition to reinfection with Schistosoma haematobium after treatment with praziquantel in Mali.

The effect of age, previous intensity of infection, and exposure on reinfection with Schistosoma haematobium after treatment was studied in a cohort of 468 subjects six years of age and over living in an irrigation scheme area in Mali. Prevalence and intensity of S. haematobium infection were measured each year between 1989 and 1991, but the reinfection study period was restricted to the last year of the follow-up. Observations were made at the principal water contact sites where the number of Bulinus truncatus shedding furcocercous cercariae was recorded. A cumulative index of exposure taking into account time, duration and type of contact, and malacologic data was calculated for each subject. Univariate analysis showed that the reinfection risk decreased with age and increased with exposure and pretreatment intensity. These results were confirmed by fitting a logistic model that showed that this risk was seven times lower among those 15 years of age and older than among the 6-14-year-old children, while linear trends with exposure to infection and pretreatment intensity were significant. This study supports the concept of an age-acquired resistance to reinfection and is in favor of a predisposition to infection that raises the question of a genetic factor controlling susceptibility/resistance to S. haematobium infection.

Adolescent↗
PubMed2002

The influence of cryoprotective media and processing procedures on motility and migration of frozen-thawed human sperm.

AIM: The study was designed to examine the effects of cryoprotective media, and glycerolating and thawing procedures on human sperm motility and gel penetrating ability. METHOD: Fifteen unselected donors provided semen varying in quality that was distributed in a factorial design across three cryoprotectants (glycerol, egg yolk-citrate-glucose-glycerol and egg yolk-tris-glucose-glycerol). Also, glycerol was added at room temperature versus at 4 degrees C. Two thaw temperatures were tested (laboratory air temperature for 10 min versus a 65 degrees C waterbath for 4 seconds). The proportion of total and progressively motile sperm was estimated immediately after thawing and following incubation at 35 degrees C for 2 h. Migration of sperm for 30 min at 37 degrees C through polyacrylamide gel was tested. RESULTS: Donors differed greatly, with post-thaw total motility of sperm ranging from 9 to 44% (P<0.05). Egg yolk-citrate-glucose-glycerol and egg yolk-tris-glucose-glycerol were superior to glycerol alone (post-thaw values of 35, 37 and 21%, respectively, P<0.05). This was due primarily to poor sperm survival when semen was cooled to 4 degrees C without glycerol or egg yolk. The two thaw temperatures gave similar results. Sperm migration tests paralleled the motility results, but were more sensitive in detecting differences. CONCLUSION: Egg yolk, particularly in a tris-based medium that is widely used in domestic animals, improved the cryopreservation of both good and poor quality human semen.

Cryopreservation↗
PubMed1962

Live tissue-culture influenza vaccine.

With a view to improving the quality of live influenza vaccines (previously passaged on eggs) in the USSR, attempts were made to obtain vaccine strains of virus by recent tissue-culture methods.Strains of A2 and B viruses obtained from patients in influenza epidemics were isolated on chick embryos and cultured by serial passage on monkey-kidney tissue or skin-muscle tissue of human embryos; a variant strain was obtained by further passaging of tissue-culture virus fluid through chick embryos. These strains all became gradually adapted to the tissue-culture and were generally stabilized by the 10th to 13th passage.Intranasal insufflation of the vaccine into volunteers resulted in twofold to eightfold antibody increases in the great majority and gave rise to almost no reactions.Lyophilization of the strains with sucrose-gelatin or calf serum ensured the stability of the vaccines for periods of up to six months.

Administration, Intranasal↗
PubMed1987

Influence of Florida 301 wheat in a laying hen diet on egg yolk rupture strength.

A study was designed to determine whether wheat could be substituted for corn without reducing yolk quality and yolk membrane strength. Diets with either corn or Florida 301 wheat as the grain source were fed to 50-wk-old hens (140 per diet). Eggs were collected and stored at 10 C for up to 4 wk or at 23 C for 1 wk. At weekly intervals Haugh units, yolk index, yolk rupture strength, and yolk deformation distance at rupture were measured and compression percentages were calculated. Haugh units and yolk index were not affected by diet. Yolk rupture strength and deformation were 12.3% and 4.7% greater, respectively, for eggs from hens on the wheat diet than for those from hens on the corn diet. Both rupture strength and deformation declined significantly with storage. Eggs stored at 23 C were lower in yolk rupture strength and deformation than those held at 10 C. Percentage of compression at rupture also declined with storage, but the decline was initially more rapid for egg yolks from birds fed the corn diet than for egg yolks from birds fed the wheat diet. It was concluded that Florida 301 wheat may be substituted for corn without incurring any problems in the quality of the yolk and that yolk breaking strength would be enhanced.

Animal Feed↗
PubMed2003

Food quality controls reproduction of the zebra mussel (Dreissena polymorpha).

Species such as Dreissena polymorpha sometimes contribute substantially in the transfer of primary to secondary production. During the ontogenetic cycle, the reproductive investment of adult mussels is one of the main parameters that affect recruitment success. We studied how food quality and temperature affect the reproductive investment in term of egg mass of D. polymorpha in a lake by sampling mussels monthly from 4 m and 15 m depths. Temperature affected reproduction directly and also indirectly through the food. To assess whether temperature and/or food conditions led to the differences observed in mussels sampled from the two depths, mussels were reared in the laboratory under two different temperature regimes for 3 months, simulating the temperature of the lake at 4 m and 15 m depth. Possible effects of food quality were tested at each temperature using four diets differing in fatty acid composition. Temperature played an important role as a trigger for spawning, and the type of diet clearly affected the reproductive investment. When the heterokont chromophyte alga Nannochloropsis limnetica, which is rich in polyunsaturated fatty acids (PUFAs) and long-chained PUFAs (>C18), was fed to mussels, an increased egg mass was obtained. This result was in contrast to that found when the green alga Scenedesmus obliquus and the cyanobacterium Aphanothece sp., both of which are deficient in long-chained PUFAs, were offered as food to the mussels. Such a PUFA-dependent food quality may affect reproduction in lakes. Food quality effects vary seasonally in a lake and may be most important in summer, when low-food-quality green algae and cyanobacteria are abundant. The low biochemical quality of these blooms may affect at least the later period of gametogenesis of D. polymorpha, which reproduces from June to August.

Animals↗