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At least 973 records · Page 54Linked to original sources
PubMed2003

Abnormal spermatogenesis at low temperatures in the Japanese red-bellied newt, Cynops pyrrhogaster: possible biological significance of the cessation of spermatocytogenesis.

In newt testis, spermatocytes never appear during winter, because secondary spermatogonia die by apoptosis just before meiosis. In the current study, we examined the effect of low temperatures on spermatogenesis. Incubation of newts at low temperatures (8, 12, 15 degrees C) induced defects in spermatogenesis in a temperature-dependent manner. At 8 degrees C, multinucleated giant cells (MGCs) were observed in spermatocytes and spermatogenesis never proceeded beyond meiosis. Although spermatocytes completed meiotic divisions at 12 degrees C, severe cell death was observed in the spermatids. At 15 degrees C both normal and abnormal spermiogenesis were observed. Under these conditions, impaired meiotic synapsis/recombination and down-regulation of the expression of the DMC1 protein, which play pivotal roles in meiotic pairing in eukaryotes, were also observed. Furthermore, to examine the quality of the sperm produced at low temperature for supporting development, artificial insemination was performed. The eggs inseminated with spermatozoa derived from newts kept at 15 degrees C demonstrated a restricted developmental capacity, even though these spermatozoa had an equal capacity for carrying out fertilization to those kept at 22 degrees C. These results suggest that meiosis at low temperatures cause the production of abnormal spermatozoa. Conservation and the significance of this phenomenon in poikilothermic vertebrates living in the temperate zones are also discussed.

Animals↗
PubMed2000

Ovicide in the whitefly parasitoid, Encarsia formosa.

The oviposition decisions made by insect parasitoids when encountering hosts of variable quality have been the subject of extensive theoretical and experimental investigation. For parasitoids that lay their eggs inside the host, the possible outcomes of encounters with parasitized hosts have been assumed to include only oviposition (superparasitism), rejection, or in some cases feeding on host haemolymph. We document another outcome in Encarsia formosa Gahan (Hymenoptera: Aphelinidae), a species that has been a model system for the study of oviposition behaviour. In E. formosa, females may kill eggs previously laid within the host by jabbing them with their ovipositor before ovipositing themselves. (1) Our observations indicated that jabbed eggs were indeed killed. (2) In experimental arenas in the laboratory, ovicide occurred in the majority of encounters with parasitized hosts and at highest frequency in encounters resulting in oviposition. (3) There was no significant difference in the handling time associated with oviposition+ovicide in parasitized hosts in comparison with oviposition alone, suggesting that there is no time cost to ovicide. (4) Ovicide did not appear to be incidental to normal probing within a host. Radial analysis of the direction of ovipositor movement with respect to the centre of the previously laid egg within the host showed that females engaged in ovicidal bouts probed most often in the direction of the egg. This is the first well-documented study of ovicide in an endoparasitoid. We suggest ovicide may be under-reported in other endoparasitoid species due to the difficulty of observing it. Copyright 2000 The Association for the Study of Animal Behaviour.

Journal Article↗
PubMed1995

Possibilities of the non-invasive electrogastrography.

A non-invasive method for recording the electrical activity of the gastric muscle wall is presented. Electrogastrograms (EGG) with cutaneous electrodes on the abdominal wall were recorded using an original electrogastrograph. High-quality records without cardiac artifacts allowed for identification of waves belonging to the quiescent or activity period of the migrating myoelectric complex (MMC). The amplitude of the waves of the activity period of MMC were almost twice higher than that of the waves of the quiescent period. The wave amplitude immediately after feeding increased two times and a half compared to that during fasting. The high-amplitude waves in the activity periods of MMC and after feeding in the electrogastromyograms (EGMG) of dogs corresponded to bursts of spike potentials with slow potentials, i.e. to intense gastric muscle wall contractions. The method could contribute to the diagnosis of gastric motility disturbances in clinical practice.

Action Potentials↗
PubMedDate not supplied

Development of a new series of agricultural/food reference materials for analytical quality control of elemental determinations.

Ten new Agricultural/Food Reference Materials--Bovine Muscle Powder (National Institute of Standards and Technology [NIST], code NIST RM 8414), Whole Egg Powder (NIST RM 8415), Microcrystalline Cellulose (NIST RM 8416), Wheat Gluten (NIST RM 8418), Corn Starch (NIST RM 8432), Corn Bran (NIST RM 8433), Whole Milk Powder (NIST RM 8435), Durum Wheat Flour (NIST RM 8436), Hard Red Spring Wheat Flour (NIST RM 8437) and Soft Winter Wheat Flour (NIST RM 8438)--were prepared by application of milling, irradiation, sieving, blending, and packaging procedures. Excellent material homogeneity was found for virtually all major, minor, and trace elements of interest. The reference materials were characterized with respect to elemental composition via an extensive international, interlaboratory characterization (certification) campaign. Chemical analyses conducted in 73 cooperating laboratories applying 13 major classes of independently different analytical methods led to 278 concentration values for 34 nutritionally, toxicologically, and environmentally pertinent elements. A total of 213 best-estimate and 65 informational concentration values are available for Al, As, B, Ba, Br, Ca, Cd, Cl, Co, Cr, Cs, Cu, F, Fe, Hg, I, K, Mg, Mn, Mo, N, Na, Ni, P, Pb, Rb, S, Sb, Se, Sr, Ti, V, W, and Zn. These products make a substantial contribution to the existing world repertoire of biological reference materials with respect to natural matrix and elemental composition. They are expected to be useful to analysts for quality control of analytical data. Applications include evaluations of analytical methods and instruments used in nutritional, toxicological, monitory, regulatory, environmental, agricultural, and other investigations. These products are available to the analytical community from the Standard Reference Materials Program, NIST, Gaithersburg, MD.

Analysis of Variance↗
PubMed1997

The steroid pheromone 4-pregnen-17,20ss-diol-3-one increases fertility and paternity in goldfish.

Previous studies in goldfish (Carassius auratus) showed that the oocyte maturation-inducing steroid 4-pregnen-17,20ss-diol-3-one (17,20ssP) functions after release as a pheromone that increases male serum gonadotropin II (GtH II) concentration, milt (sperm and seminal fluid) volume and sexual activity, effects hypothesized to increase male reproductive success in the sperm competition of multi-male spawnings. The present study tested this hypothesis by determining whether overnight exposure to 17,20ssP increases fertility. In pair spawnings, 17,20ssP-exposed males fertilized a greater percentage of eggs than did control males, apparently because 17,20ssP-exposed males had more releasable sperm at the onset of spawning. Microsatellite DNA paternity analysis showed that 17,20ssP-exposed males also fertilized more eggs in competitive spawnings involving one control male and one 17,20ssP-exposed male. This effect of 17,20ssP on competitive fertility could be due to demonstrated increases in spawning activity, milt volume, duration of sperm motility and proportion of motile sperm. However, it appears that a change in sperm quality is a major component of the pheromonal effect because, in competitive in vitro fertilizations, sperm from 17,20ssP-exposed males fertilized more eggs than did sperm from control males. The results indicate that the response to pheromonal 17,20ssP is a major determinant of reproductive success in male goldfish.

Journal Article↗
PubMed1975

Some responses of laying hens to induced arrest of egg production.

Arrest of egg production was induced by forced-molt (artificial light deprivation and feed deprivation for 10 days followed by 20 days of grain only) and by low-calcium regime in one experiment, and by Nicarbazin in another. Post-arrest production and shell quality significantly surpassed the control in the force-molt but not in the low-Ca treatment. At the onset of production, following the pause, egg weight and shell weight per unit of surface area rapidly increased up to the 9-10th egg. In the second trial, feed intake declined in about one week after the arrest in egg production to a non-layer level. During this week, body weight increased. However, despite the increase in feed intake after the onset of production, pre-arrest levels were not obtained even after 11 days, resulting in a loss of body weight. The separation of flock production into its components, rate of production of the layers, and the proportion of layers in the flock, is proposed.

Animal Feed↗
PubMed1997

In vivo rat assay for true protein digestibility and protein quality of beef and meat products extended with soy protein.

The protein quality of ten food products in including beef, bovine rumen and four meat products extended with soy proteins had been evaluated by rat feeding experiment; defatted freeze-dried whole egg served as a reference protein. Mean endogenous fecal and metabolic urinary nitrogen amounted to 1.01 and 1.11 mg/g food consumed, respectively. True protein digestibility and biological value of beef averaged 90.3% and 82.6%, respectively. The protein qualities of bovine rumen are quite similar to that of beef. Beef products extended with soy protein are quite inferior in their true protein digestibilities (81.4-84.6%) and biological value (68.8-76.0%) as compared to beef. The utilizable protein of extended meat fluctuated between 22.6-29.3% compared with a mean level of 70% in beef.

Animals↗
PubMed2001

Assessment of sperm quality: a flow cytometric approach.

For many years, scientists have sought to develop laboratory assays that accurately predict the fertilizing capacity of a semen sample. This goal, however, has proven elusive and will most likely be very difficult to achieve, due to the complex nature of the problem. Part of the problem results from the many attributes that a spermatozoon must possess to fertilize an egg, and how laboratory assays can evaluate all of these attributes simultaneously. The percentage of motile sperm in a sample is most commonly used to evaluate semen quality. This assay, however, is not highly correlated with the fertilizing capacity of semen samples. One reason motion assays do not correlate well with fertility is that we are evaluating only one of many attributes that a sperm must possess to fertilize an oocyte. One of the problems of measuring multiple sperm attributes is the time and cost required. Using flow cytometric assays, multiple sperm attributes, including cell viability, acrosomal integrity, and mitochondrial function, can be measured simultaneously in sperm cells. In addition, the ability of sperm to undergo capacitation and the acrosome reaction, as well as the chromosomal integrity of sperm can be measured using flow cytometry. Flow cytometry permits us to evaluate 50,000 sperm in less then 1 min and at reasonable cost. Although flow cytometry is a powerful tool for evaluating many sperm attributes, it cannot evaluate all of the attributes a sperm cell requires to fertilize an oocyte. Therefore, laboratory assays are also being developed to evaluate the ability of sperm: (1) to bind to the oocyte, by evaluating the ability of sperm to bind to the perivitelline membrane of the hen egg in vitro; (2) to undergo an acrosome reaction in vitro, after treatment with membrane destabilizing compounds; and (3) to penetrate oocytes in vitro. When data from multiple sperm assays are used, higher correlations with the fertilizing potential of a semen sample is achieved. For example, in a study conducted utilizing five stallions, the percentage of motile sperm in semen samples correlated poorly with fertility (r(2)=0.22), however, when data for sperm motility, viability and penetration rates into zona-free hamster oocytes were utilized together, these data explained 72% of the differences in the fertility of the stallions (r=0.849; [Theriogenology 46 (1996) 559]). Armed with a battery of tests, which evaluate many different sperm attributes, researchers should be able to more accurately estimate the fertilizing potential of semen samples.

Acrosome↗
PubMed2002

Surface and subsurface irrigation with effluents of different qualities and presence of Cryptosporidium oocysts in soil and on crops.

A large variety of human pathogens are excreted in wastewater including bacteria, viruses, protozoan cysts and helminth eggs. In raw sewage, human pathogens reach high numbers, thereafter decreasing successively at each treatment step. However, the final effluents still contain a large fraction of these pathogens that may pose a serious public health. Among the various crops irrigated with effluents, vegetables are the most vulnerable to contamination. Vegetables, usually eaten raw (uncooked) or with rich dressings (causing regrowth of some pathogenic bacteria) pose the main threat to humans. The importance of microbiological and parasitological criteria for reused water has been repeatedly emphasized. Some microbiological recommendations based on epidemiological data have been established for untreated wastewater, there is still a need to define the criteria for effluent quality required for unrestricted crop irrigation. This paper presents a field study comparison of two irrigation methods: surface and subsurface of field crops (mainly vineyard) and follow-up of Cryptosporidium oocysts in soil at different depths (0 to 90 cm). Oocysts were isolated at all depths without a clear pattern of distribution (0 to 640 oocysts/g). In addition different vegetables irrigated with different effluent qualities were tested for the presence of Cryptosporidium oocysts and Giardia cysts. The highest prevalence of oocysts was found on zucchini that has a sticky and hairy outer surface (80 to 10,000 oocysts/0.5 kg).

Agriculture↗
PubMed2003

Alternative procedures for molt induction: practical aspects.

Shortening daylight (to 10.5 to 11 h/d) slightly reduced the rest period (the interval between last egg and first clutch), whereas feeding a low-protein diet during the 22-d period following 8 d of feed withdrawal (FW) (recovery period) markedly extended it. Feed withdrawal accompanied by a short-daylight regime and a long recovery period led to the best postmolt production. However, production per hen housed during the whole experimental period was only slightly increased. Thus, a long rest period may mask the positive effects of short daylight and recovery diet. At least 140 to 170 d were needed to enable the molted hens to compensate for the loss of eggs during the rest period. Therefore, under certain economic conditions, rearing of nonmolting hens for 640 to 700 d should be an economic consideration. Ten days of feeding of a diet containing 0.06% nicarbazin (NICR) arrested egg production and caused a 22-d rest period but not a typical molt. Few variables of production or shell quality were improved by NICR but to a lesser extent than by FW or Zn feeding. Five days of feeding on a high-Zn diet (20 g Zn/kg; HZn) improved postmolt performances similarly to FW. Ten days of feeding on a modest-Zn (2.8 g Zn/kg), low-Ca, and low-P diet (Zn-CaP) affected postmolt performances inconsistently. In one out of two trials (trial 2), the effects of Zn-CaP were similar to those of FW or HZn; in the other (trial 3), the effects were less pronounced, more time was required for egg arrest, and more eggs were laid occasionally during the rest period. In trial 2, only the Zn-CaP diet was accompanied by short daylight. In both trials, feed intake during the induction period was only slightly reduced. Zn feeding increased the yolk Zn content slightly in eggs laid during the induction period and at the onset of production. In trial 2, only Zn-CaP markedly increased yolk Zn of eggs laid during the first 5 d of production.

Animal Feed↗
PubMed1982

Protein evaluation of mixed diets in young adults, growing pigs, and growing rats.

The protein quality of mixed diets was tested using the nitrogen balance technique with a slope-ratio approach in adults, growing pigs, and rats. For diet A (milk, cereals, potatoes, meat, fish, and vegetables) and diet B (milk, cereals, and potatoes) the slope of the regression line, nitrogen balance = f (nitrogen intake) was calculated and expressed in percentage of the slope obtained for diets containing egg white protein. In man, diet A was significantly better than the egg white protein diet which was similar to diet B. In pigs, diets A and B were significantly better than egg white protein. In rats, egg white protein was significantly better than diets A and B. The results are of interest in relation to the recommendations by FAO/WHO regarding adjustment of protein allowance in relation to dietary protein quality.

Adult↗
PubMedDate not supplied

[Effect of different food stimuli on pancreatic exocrine function in ontogeny].

The fermentative adaptation of the pancreas to the quality of food through determination of the amylase, lipase and proteases activity in the contents of the small intestine and the gland homogenate on an empty stomach and 2 hours feeding on the egg white, bread and walnuts were studied in chickens aged 1-60 days. The 1-2 day old chicken are shown to lack the ability to adapt the gamut of pancreatic enzymes to the quality of the stimulant. This ability appears on the 5th day and becomes persistent by the 20th day of life. The adaptability of pancreatic enzymes manifests itself in a predominant rise of the lipolytic activity of the chyme after feeding on a fat stimulant and in the activity of proteases after feeding on protein. In paultry of the age under consideration the fermentative adaptability to carbohydrate food is lacking.

Amylases↗
PubMed2003

A semiquantitative approach for evaluating safety assurance levels for Salmonella spp. throughout a food production chain.

Various safety assurance measures are implemented in Switzerland throughout the food production chain to prevent foods of animal origin from being contaminated with Salmonella. The data that are generated from the implementation of these measures are dispersed and heterogeneous. This hinders a general overview and makes a comprehensive national evaluation of the safety assurance level difficult. A semiquantitative method that considers the quality and relevance of the various safety assurance measures for Salmonella spp. was developed. The method uses the data generated from the implementation of safety assurance measures on a national basis (gathered by interviewing stakeholders in the production step). By assembling and analyzing the data systematically, the safety assurance level for Salmonella spp. can be evaluated at every step of the food production chain. This method allows the detection of strengths and weaknesses of the safety system. The systematic evaluation procedures permit comparisons between production steps and product categories. The method was used for evaluating the safety assurance levels throughout the production chain of eggs and egg products in Switzerland. Results of the analysis showed that the overall safety assurance levels for Salmonella spp. at all production steps for eggs and egg products were good. The relatively straightforward implementation of the method made it particularly appropriate in the context of a preliminary evaluation. The method does not have the same high level of detail that is provided by microbial quantitative risk assessments, but it allows an analyst to provide meaningful results when the large amount of data required for a quantitative approach are not present while including the entire "farm to fork" continuum. It may be used as a basis for more in-depth assessments of food safety levels within various production sectors. The method could be adapted for evaluating the safety assurance for other zoonotic foodborne pathogens of interest, such as Campylobacter spp.

Animals↗
PubMed2004

Parenting infants conceived by gamete donation.

In recent years, concerns have been raised regarding the potentially negative consequences of gamete donation for parent-child relationships. Findings are presented of a study of families with an infant conceived by gamete donation. Fifty donor insemination families and 51 egg donation families were compared with 80 natural conception families on standardized interview and questionnaire measures of the psychological well-being of the parents, the quality of parent-child relationships, and infant temperament. The differences that were identified indicated more positive parent-child relationships among the gamete donation than the natural conception parents, accompanied by greater emotional involvement with the child. Comparisons were also carried out between the donor insemination and the egg donation parents on their experiences of gamete donation. In contrast to the findings of earlier investigations, the donor insemination and egg donation parents appeared to be more open toward disclosing the donor conception to the child. It was concluded that infants conceived by egg or sperm donation did not appear to be at risk for parenting difficulties.

Adult↗
PubMed2000

How incubation temperature influences the physiology and growth of embryonic lizards.

Eggs of two small Australian lizards, Lampropholis guichenoti and Bassiana duperreyi, were incubated to hatching at 25 degrees C and 30 degrees C. Incubation periods were significantly longer at 25 degrees C in both species, and temperature had a greater effect on the incubation period of B. duperreyi (41.0 days at 25 degrees C; 23.1 days at 30 degrees C) than L. guichenoti (40.1 days at 25 degrees C; 27.7 days at 30 degrees C). Patterns of oxygen consumption were similar in both species at both temperatures, being sigmoidal in shape with a fall in the rate of oxygen consumption just prior to hatching. The higher incubation temperature resulted in higher peak and higher prehatch rates of oxygen consumption in both species. Total amount of oxygen consumed during incubation was independent of temperature in B. duperreyi, in which approximately 50 ml oxygen was consumed at both temperatures, but eggs of L. guichenoti incubated at 30 degrees C consumed significantly more (32.6 ml) than eggs incubated at 25 degrees C (28.5 ml). Hatchling mass was unaffected by either incubation temperature or the amount of water absorbed by eggs during incubation in both species. The energetic production cost of hatchling B. duperreyi (3.52 kJ x g(-1)) was independent of incubation temperature, whereas in L. guichenoti the production cost was greater at 30 degrees C (4.00 kJ x g(-1)) than at 25 degrees C (3.47 kJ g(-1)). Snout-vent lengths and mass of hatchlings were unaffected by incubation temperature in both species, but hatchling B. duperreyi incubated at 30 degrees C had longer tails (29.3 mm) than those from eggs incubated at 25 degrees C (26.2 mm). These results indicate that incubation temperature can affect the quality of hatchling lizards in terms of embryonic energy consumption and hatchling morphology.

Animals↗