Cryopreservation of Sheep Primordial Follicles

The aim of this study was to evaluate the efficiency of 1 M dimethylsulphoxide (DMSO), ethylene glycol (EG), propylene glycol (PROH) and glycerol (GLY) to cryopreserve primordial follicles. The first evaluation was performed soon after cryopreservation and the second evaluation after 4 days of in vitro culture, using the cryoprotectants that allowed the higher results (higher follicular survival rate) after cryopreservation. The results after follicular isolation (control) and cryopreservation using 1 M DMSO, EG, PROH and GLY showed that the mean number (+/- SEM) of live follicles per millilitre was 3204 (100%) +/- 319.27, 2798 (87%) +/- 239.14, 2492 (78%) +/- 345.8, 448 (14%) +/- 46.3 and 208 (7%) +/- 75.26, respectively. Higher follicular survival was reported when DMSO and EG were used. Control follicles and follicles cryopreserved with these two cryoprotectants were cultured and the percentage of follicular survival was 55% (control), 42% (EG) and 34% (DMSO). Similar results were found between control and follicles cryopreserved with EG. In conclusion, 1 M EG is the most effective cryoprotectant to preserve primordial follicles isolated from ovaries of sheep.     

Interpretation of snow-climate feedback as produced by 17 general circulation models

Snow feedback is expected to amplify global warming caused by increasing concentrations of atmospheric greenhouse gases. The conventional explanation is that a warmer Earth will have less snow cover, resulting in a darker planet that absorbs more solar radiation. An intercomparison of 17 general circulation models, for which perturbations of sea surface temperature were used as a surrogate climate change, suggests that this explanation is overly simplistic. The results instead indicate that additional amplification or moderation may be caused both by cloud interactions and longwave radiation. One measure of this net effect of snow feedback was found to differ markedly among the 17 climate models, ranging from weak negative feedback in some models to strong positive feedback in others.     

Differential Expression of IGF Family Members in Heat‐Stressed Embryos Produced In Vitro from OPU‐Derived Oocytes of Nelore (Bos indicus) and Holstein (Bos taurus) Cows

The IGF system is related to embryo quality. We aim to determine the effect of the heat stress on the mRNA expression of IGF1 and IGF2, IGFR1 and IGFR2, IGFBP2 and IGFBP4, and PAPPA in in vitro production (IVP) blastocysts from Nelore and Holstein after ovum pick up (OPU) to better understand the differences between these breeds. Oocytes from four Nelore and seven Holstein were collected in six OPU sessions. Following in vitro maturation and fertilization using six Nelore or Holstein sires, embryos were divided into control (cultured at 39°C) and heat stress (HS; exposed to 41°C for 9 h). Blastocysts were submitted to RNA extraction. The IGF1 expression was higher in blastocysts under HS in both breeds, and the expression of IGFBP2 and IGFBP4 was higher in Holstein blastocysts under HS. The high PAPPA expression and the low expression of IGFBP2 and IGFBP4 are associated with a more efficient degradation of IGFBPs, which results in greater IGF bioavailability in Nelore blastocysts and may contribute to the superior HS tolerance in Nelore, when compared to Holstein.     

Correlations between ground and excited state spectra of a quantum Dot

The ground and excited state spectra of a semiconductor quantum dot with successive electron occupancy were studied with linear and nonlinear magnetoconductance measurements. A direct correlation was observed between the mth excited state of the N-electron system and the ground state of the (N + m)-electron system for m up to 4. The results are consistent with a single-particle picture in which a fixed spectrum of energy levels is successively filled, except for a notable absence of spin degeneracy. Further departures from the single-particle picture due to electron-electron interaction were also observed. Magnetoconductance fluctuations of ground states show anticrossings where wave function characteristics are exchanged between adjacent levels.     

Slow fertilization of stickleback eggs: the result of sexual conflict?

Background  

The fertilization success in sperm competition in externally fertilizing fish depends on number and quality of sperm. The time delay between sequential ejaculations may further influence the outcome of sperm competition. Such a time interval can load the raffle over fertilization if fertilization takes place very fast. Short fertilization times are generally assumed for externally fertilizing fish such as the three-spined stickleback (Gasterosteus aculeatus). In this pair-spawning fish, territorial males often try to steal fertilizations in nests of neighbouring males. This sneaking behaviour causes sperm competition. Sneakers will only get a share of paternity when eggs are not fertilized immediately after sperm release. Contrary to males, females may be interested in multiple paternity of their clutch of eggs. There thus may be a sexual conflict over the speed of fertilization.     

Endotracheal intubation in horses: a study of two cuff inflation pressures, correlation with liquid aspiration, and tracheal wall damage

Nine adult horses were anesthetized for a nonsurvival abdominal adhesion study. Horses were randomly assigned into two groups to receive endotracheal tube cuff pressures of either 80 cm H₂O (Group P80) or 120 cm H₂O (Group P120). After intubation (Bivona 30 mm ID), anesthesia was maintained with isoflurane. Horses were ventilated 10 times per minute with a suitable inspiratory pressure to maintain Pe ′CO₂ in the 35–40 mm Hg (4.7–6.0 kPa) range. Cuff pressure was continuously monitored with a pressure transducer (TruWave, Baxter) calibrated to the atmospheric pressure and maintained at a constant pressure. Twenty‐five millilitres of methylene blue dye in saline were instilled proximal to the cuff over 5 minutes. The horses were euthanized 123 ± 23 minutes later (mean ± SD). Immediately, the trachea was opened distal to the tip of the endotracheal tube, and the mucosa was observed for evidence of dye leaking past the cuff. The cervical trachea was resected and the lumen exposed by a ventral longitudinal incision. Biopsies (1–2 rings) were obtained at mid‐cuff level and distal to the tip of the endotracheal tube, and placed in formalin for later histologic examinations (H&E stain). Methylene blue stain was not observed distal to the endotracheal tube cuff in any horse. Visual examination of the tracheal mucosa revealed hyperemic or hemorrhagic lesions at the level of cuff contact both ventrally and dorsally. Histologic changes included epithelium damage, submucosal neutrophil infiltrates, and acute submucosal hemorrhages. P80 horses had none or focal to multifocal lesions on the ventral and dorsal aspects of the rings. P120 horses had multifocal to diffuse lesions on all aspects (dorsal, ventral, and lateral). We concluded that the endotracheal tube cuff produced a seal sufficient to prevent leakage at both pressures. Tracheal damages on gross and microscopic examinations were more severe and occurred more frequently at the higher cuff pressure.     

Seasonal Changes in Testicular Cell Morphology in Domestic Male Cats (Felis catus)

The aim of this study was to asses the variation in the morphology of the seminal epithelium in relation to natural photoperiod in male cats. Tom cats (n = 240) were castrated every other week throughout the year. Each testis was fixed in Bouin's solution and cut into sections. The percentage of tubules with round spermatids (RS), elongated spermatids (ES), tailed spermatids (TS), mature spermatids (MS) and the number of Sertoli cells (SC) and Leydig cells (LC) were recorded in each sample. Testicles from males during short days (SHD) had a higher percentage of tubules with RS and ES compared to testicles from males during long days (LHD, 31.3 ± 0.6 vs 2.1 ± 0.6%, p < 0.001; 30.9 ± 0.7 vs 11.0 ± 0.7%, p < 0.001). Conversely, testicles from males during SHD had a lower percentage of tubules with TS and MS compared to testicles from males during LHD (24.5 ± 0.8 vs 29.7 ± 0.8%, p < 0.01; 13.1 ± 1.2 vs 57.0 ± 1.2%, p < 0.01). Furthermore, testicles from males during SHD had a higher number of SC and lower number of LC compared to testicles from males during LHD (11.4 ± 0.1 vs 8.0 ± 0.1%, p < 0.01; 19.2 ± 1.0 vs 38.0 ± 1.0%, p < 0.01). In conclusion, there are seasonal changes in testis cell morphology in the tom which may be related to seasonal sperm production.