The number of mitochondria in Xenopus laevis ovulated oocytes

An attempt was made to estimate the total number of mitochondria in Xenopus laevis ovulated oocytes. For this purpose the necessary basic parameters were calculated employing planimetry and simple mathematical formulas. It was found that the number of mitochondria in the ovulated oocyte of Xenopus is of the order of 10(7). The significance of this finding is discussed.     

Childbearing may increase visceral adipose tissue independent of overall increase in body fat

Objective: To examine whether childbearing is associated with increased visceral adiposity and whether the increase is proportionally larger than other depots. Methods and Procedures: This prospective study examined changes in adiposity assessed via computed tomography (CT) and dual‐energy X‐ray absorptiometry among 122 premenopausal women (50 black, 72 white) examined in 1995–1996 and again in 2000–2001. During the 5‐year interval, 14 women had one interim birth and 108 had no interim births. Multiple linear regression models estimated mean (95% confidence interval (CI)) 5‐year changes in anthropometric and adiposity measures by interim births adjusted for age, race, and changes in total and subcutaneous adiposity. Results: We found no significant differences between one interim birth and no interim births for 5‐year changes in weight, BMI, total body fat, subcutaneous adipose tissue, or total abdominal adipose tissue. Visceral adipose tissue increased by 40 and 14% above initial levels for 1 birth and 0 birth groups, respectively. Having 1 birth vs. 0 births was associated with a greater increase in visceral adipose tissue of 18.0 cm² (4.8, 31.2), P < 0.01; gain of 27.1 cm² (14.5, 39.7) vs. 9.2 cm² (4.8, 13.6), and a borderline greater increase in waist girth of 2.3 cm (0, 4.5), P = 0.05; gain of 6.3 cm (4.1, 8.5) vs. 4.0 cm (3.2, 4.8), controlling for gain in total body fat and covariates. Discussion: Pregnancy may be associated with preferential accumulation of adipose tissue in the visceral compartment for similar gains in total body fat. Further investigation is needed to confirm these findings and determine whether excess visceral fat deposition with pregnancy adversely affects metabolic risk profiles among women.     

Changing climate in Hungary and trends in the annual number of heat stress days

Global climate change can have serious direct effects on animal health and production through heat stress. In Hungary, the number of heat stress days per year (YNHD), i.e., days when the temperature humidity index (THI) is above a specific comfort threshold, has increased in recent years based on observed meteorological data. Between 1973 and 2008, the countrywide average increase in YNHD was 4.1% per year. Climate scenarios based on regional climate models (RCM) were used to predict possible changes in YNHD for the near future (2021–2050) relative to the reference period (1961–1990). This comparison shows that, in Hungary, the 30-year mean of YNHD is expected to increase by between 1 and 27 days, depending on the RCM used. Half of the scenarios investigated in this study predicted that, in large parts of Hungary, YNHD will increase by at least 1 week. However, the increase observed in the past, and that predicted for the near future, is spatially heterogeneous, and areas that currently have large cattle populations are expected to be affected more severely than other regions.     

Assessment of in vitro fertility of deer spermatozoa by heterologous IVF with zona-free bovine oocytes

We have previously shown that the in vitro development of deer embryos differed according to the IVF conditions. The aim of the study was to use heterologous IVF with zona-free matured bovine oocytes to assess the in vitro fertility of 3 samples of deer semen (2 ejaculates from sika deer (Cervus nippon) and 1 pool of epididymal spermatozoa from red deer (Cervus elaphus)). The frozen/thawed semen samples were selected on Percoll gradient and resuspended in Tyrode modified medium supplemented with estrus sheep serum (0, 2, 20% v/v) or heparin (10 microg/mL). During 8 h of culture, the sperm motility index according to the post-insemination time (hpi) did not differ either between samples or between supplemented IVF media. In vitro matured zona-free bovine oocytes were inseminated in different IVF media with the semen samples. Penetration rates assessed at 15 hpi were optimal with 20% estrus sheep serum for sika deer ejaculates whereas 2% were sufficient to reach the maximum functionality of epididymal spermatozoa from red deer. The mean time of pronuclear formation was similar regardless of the semen sample. The precocity of the onset of the first S-phase in both pronuclei was characterized by Bromo-deoxy-Uridine exposures between 5 and 15 hpi in order to assess the developmental potential conferred by the semen sample (intrinsic value). As we previously observed in homologous IVF, this value seemed to be higher for the epididymal sperm sample.     

Developmental competence of different quality bovine oocytes retrieved through ovum pick-up following in vitro maturation and fertilization

In the present study, oocytes retrieved from cross bred Karan Fries cows by ovum pick-up technique were graded into Group 1 and Group 2, based on the morphological appearance of the individual cumulus–oocyte complexes (COCs). To analyze whether the developmental potential of the COCs bears a relation to morphological appearance, relative expression of a panel of genes associated with; (a) cumulus–oocyte interaction (Cx43, Cx37, GDF9 and BMP15), (b) fertilization (ZP2 and ZP3), (c) embryonic development (HSF1, ZAR1 and bFGF) and (d) apoptosis and survival (BAX, BID and BCL-XL, MCL-1, respectively) was studied at two stages: germinal vesicle (GV) stage and after in vitro maturation. The competence was further corroborated by evaluating the embryonic progression of the presumed zygotes obtained from fertilization of the graded COCs. The gene expression profile and development rate in pooled A and B grade (Group 1) COCs and pooled C and D grade (Group 2) COCs were determined and compared according to the original grades. The results of the study demonstrated that the morphologically characterized Group 2 COCs showed significantly (P<0.05) lower expression for most of the genes related to cumulus–oocyte interplay, fertilization and embryonic development, both at GV stage as well as after maturation. Group 1 COCs also showed greater expression of anti-apoptotic genes (BCL-XL and MCL1) both at GV stage and after maturation, while pro-apoptotic genes (BAX and BID) showed significantly (P<0.05) elevated expression in poor quality COCs at both the stages. The cleavage rate in Group 1 COCs was significantly higher than that of Group 2 (74.46±7.06 v. 31.57±5.32%). The development of the presumed zygotes in Group 2 oocytes proceeded up to 8- to 16-cell stages only, while in Group 1 it progressed up to morulae (35.38±7.11%) and blastocyst stages (9.70±3.15%), indicating their better developmental potential.     

Intracytoplasmic sperm injection may increase the risk of imprinting defects

In germ cells and the early embryo, the mammalian genome undergoes widespread epigenetic reprogramming. Animal studies suggest that this process is vulnerable to external factors. We report two children who were conceived by intracytoplasmic sperm injection (ICSI) and who developed Angelman syndrome. Molecular studies, including DNA methylation and microsatellite and quantitative Southern blot analysis, revealed a sporadic imprinting defect in both patients. We discuss the possibility that ICSI may interfere with the establishment of the maternal imprint in the oocyte or pre-embryo.     

A random process may control the number of endemic species

The richness of endemic species is often recognized as an indication of the distinctiveness of certain local faunas and is used for the definition of conservation hotspots as well. Faunas of different animal taxa were considered in sets of contiguous geographical units. Comparing the faunas of different units in one set, we found an exponential increase in the number of endemics when plotted against the number of non-endemics. A model of independent stochastic population dynamics under the control of environmental oscillations produces random fluctuations in the ranges of species. Ranges of endemic species are supposedly narrower than ranges of co-occurring non-endemic species. In such a case, the flow of a random process leads to an exponential relationship between numbers of co-occurring endemic and non-endemic species. This process also produces an apparent positive correlation between total species number and the percentage of endemics.     

Polymorphisms associated with egg number at 300 days of age in chickens

We looked for variations that could be associated with chicken egg number at 300 days of age (EN300) in seven genes of the hypothalamic-pituitary-gonadal axis, including gonadotrophin-releasing hormone-I (GnRH-I), GnRH receptor (GnRHR), neuropeptide Y (NPY), dopamine D2 receptor (DRD2), vasoactive intestinal polypeptide (VIP), VIP receptor-1 (VIPR-1), prolactin (PRL), and the QTL region between 87 and 105 cM of the Z chromosome. Ten mutations in the seven genes were chosen to do marker-trait association analyses in a population comprising 1310 chickens, which were obtained from a company located in Guangdong Province of China. The C1704887T of VIPR-1 was found to have a highly significant association with EN300. The T5841629C of DRD2 and the C1715301T of VIPR-1 were significantly associated with EN300. A highly significant association was also found between the C1704887T-C1715301T haplotypes of VIPR-1 and EN300. H1H3 had the highest EN300. Four PCR-RFLP variations in the candidate QTL region were selected to investigate their genetic effects on EN300. The haplotypes of T32742468C-G32742603A in this region showed a highly significant association with EN300. Bioinformatics analyses showed that both T32742468C and G32742603A were located in intron 1 of the SH3-domain GRB2-like 2 (SH3GL2) gene. We conclude that five SNPs, including C1704887T and C1715301T of VIPR-1, T5841629C of DRD2, and T32742468C and G32742603A of SH3GL2, would be useful as markers for breeding to increase chicken EN300.     

The effect of hCG administration five days after insemination on the first service conception rate of anestrous dairy cows

The aim of this study was to investigate the effect of treating anovulatory anestrous (AA) dairy cows with 1500 IU of hCG IM, 5 d after insemination, on their first service conception rate. A clinical trial was conducted during the 2003/2004 breeding season involving 442 AA dairy cows in six herds. On Day -8, all cows were treated with a progesterone-containing intravaginal device (Cue-Mate). The devices were removed on Day -2, and on Day -1 all cows received an IM injection of 1mg of estradiol benzoate. Cows in the control group (n=220) received no further treatments. Cows in the treatment group (n=222) which had been inseminated on Days 0 or 1 were treated with 1500 IU of hCG IM 5 d after insemination. Blood was collected from 30 cows (15 in each group) on Days 5 and 12 after AI for analysis of plasma P4 concentration. There was no difference in first service conception rates between the control and treatment groups (46.3% versus 43.6%, respectively; P=0.68), despite the fact that plasma P4 concentrations were higher in the treatment group on Day 12 (4.9+/-1.3 ng/mL versus 6.2+/-2.7 ng/mL for control and treatment groups, respectively; P<0.01). In conclusion, 1500 IU of hCG 5 d after insemination did not improve first service conception rate in AA dairy cows.     

Testicular responsiveness following chronic administration of hCG (1500 IU every six days) in untreated hypogonadotropic hypogonadism

The observation that the testosterone (T) response to a single intramuscular injection of hCG is prolonged suggests that currently used regimens (2-3 injections per week) to stimulate endogenous androgen secretion in hypogonadotropic hypogonadism (HH) patients have to be reassessed. Moreover, during the last few years, Leydig cell steroidogenic desensitization has been found after massive doses of hCG. The aim of the present investigation, carried out in 6 HH patients who showed no signs of puberty, was to study the effect of 1500 IU hCG administered every six days over a period of one year to induce the onset of pubertal development. To evaluate the kinetics of the response of T, 17 alpha-hydroxyprogesterone (17 alpha-OHP) and 17 beta-oestradiol (E2), blood samples were taken basally and 1, 2, 4 and 6 days after drug injection. This dynamic study was performed after the first injection and after the 4th and 12th month of treatment. During this one year time period, a progressive increase in testicular size was observed. Comparing plasma T levels (mean +/- SE) before the first injection (11.2 +/- 4.7 ng/dl) with the corresponding values at the 4th (38.7 +/- 10.5 ng/dl) and 12th months (99.5 +/- 19.9 ng/dl) of therapy, a progressive and significant increase was observed. T reached a maximum elevation 58 hours after hCG injection at the 4th month (198.3 +/- 42 ng/dl; P less than 0.01) and at the 12th month (415.6 +/- 62.6 ng/dl; P less than 0.05), whereas it remained unchanged following the first hCG injection.(ABSTRACT TRUNCATED AT 250 WORDS)     

The increase in mitochondrial DNA copy number in the tissues of gamma-irradiated mice

Changes in the number of mitochondrial DNA (mtDNA) copies in the brain and spleen tissues of gamma-irradiated (3 Gy) mice were studied by comparative analysis of the long-extension PCR products of mtDNA (15.9 kb) and a fragment of the cluster nuclear beta-globin gene (8.7 kb) amplified simultaneously in one and the same test-tube within total DNA. The analysis showed that, compared to the nuclear beta-globin gene, an increase in mtDNA copy number (polyploidization) took place in the brain and spleen cells of mice exposed to gamma-radiation. This data led to the suggestion that the major mechanism for maintenance of the mitochondrial genome, which is constantly damaged by endogenous ROS and easily affected by ionizing radiation or other exogenous factors, is the induction of synthesis of new mtDNA copies on intact or little affected mtDNA templates because the repair systems in the mitochondria function at a low level of efficiency.