Variations in the Proportion of Glycolytic/Non-glycolytic Energy Substrates Modulate Sperm Membrane Integrity and Function in Diluted Boar Samples Stored at 15–17°C

In this work the role of energy substrates in the maintenance of boar-sperm survival during storage at 15-17 degrees C was tested. For this purpose, boar spermatozoa were stored at 15-17 degrees C in several defined media with separate combinations of a monosaccharide, glucose and a non-monosaccharide, either citrate or lactate, energy substrates. Our results indicate that the medium containing the highest concentration of glucose together with low lactate levels was the most suitable to maintain sperm quality for 168 h at 15-17 degrees C. This was confirmed after observation of the results of the percentages of viability and altered acrosomes, the osmotic resistance test, the hyperosmotic resistance test and the rhythm of L-lactate production. The survival ability of boar sperm was greater in this experimental medium than in the standard Beltsville Thawing Solution extender, which contains only glucose as an energy substrate, although at a concentration far higher than that of all the tested experimental media. Our results indicate that the exact composition, more than the pure quantity of energy substrates, is a very important modulatory factor which affects survival ability of boar sperm in refrigeration. Thus, the exact combination of several energy substrates would have to be taken into account when optimizing the design of commercial extenders to store boar spermatozoa at 15-17 degrees C.     

Effects of Matrix Filtration of Low-Quality Boar Semen Doses on Sperm Quality

The aim of this work was to develop a method to enhance the sperm parameters of ejaculates with low sperm quality from Piétrain boars. Seminal doses were filtered through columns of DEAE Sephadex (length 2.5 ± 0.5 cm), CM Sephadex (length 5 ± 0.5 cm), glass wool (length 2 ± 0.5 cm) or glass bead (length 10 ± 0.5 cm), with an exit flow rate of 1 ml/40 s in all cases. For each male, 10 ml of the sperm cell-rich fraction diluted at 1 : 6 were filtered. Sperm quality was assessed before and after filtration. Sperm morphology, sperm motility and sperm concentration were determined using the computer program sca ^® 2002 Production, and sperm viability was evaluated by fluorescence multistaining. Osmotic resistance test and hyperosmotic resistance test were used to determine the osmotic resistance of spermatozoa, whereas l -lactate production estimated the metabolic activity. Results showed a decrease of sperm concentration and osmotic resistance of spermatozoa after filtration in the four matrixes. However, an increase in the frequency of viable spermatozoa with intact acrosome after filtration in glass bead columns and an increase of morphologically normal spermatozoa after filtration in Sephadex CM-50, glass wool and glass bead columns were observed. Despite the decrease in the frequency of progressive motile spermatozoa, l -lactate production and mitochondrial sheath integrity maintained constant after filtration. Our findings indicate that column filtration is an effective method to enhance the sperm quality by selecting viable and morphologically normal spermatozoa without altering DNA, plasma membrane, mitochondrial sheath integrity or inducing premature acrosome reaction.     

POSITRON EMISSION TOMOGRAPHY FEATURES OF CANINE NECROTIZING MENINGOENCEPHALITIS

A Yorkshire terrier and a Chihuahua were referred for acute onset, generalized tonic‐clonic seizures and were suspected to have meningoencephalitis based on magnetic resonance (MR) imaging findings. Brain lesions appeared hyperintense with T2‐weighted imaging and hypointense with T1‐weighted imaging, and were characteristic of necrotizing meningoencephalitis. Both dogs were diagnosed with necrotizing meningoencephalitis based on pathologic findings. Fluorine‐18 fluorodeoxyglucose positron emission tomography (FDG‐PET) was performed on both animals before euthanasia with the permission of the owner. In FDG‐PET images, these lesions seen in MR images were characterized by multifocal or diffuse hypometabolism. Our FDG‐PET results provided evidence of glucose hypometabolism in areas of necrosis and cavitation associated with necrotizing meningoencephalitis. FDG‐PET has the potential to provide valuable diagnostic information in dogs with suspected necrotizing encephalitis.     

Efficiency of Two Enucleation Methods Connected to Handmade Cloning to Produce Transgenic Porcine Embryos

The purpose of our work was to establish an efficient-oriented enucleation method to produce transgenic embryos with handmade cloning (HMC). After 41–42 h oocytes maturation, the oocytes were further cultured with or without 0.4 μg/ml demecolcine for 45 min [chemically assisted handmade enucleation (CAHE) group vs polar body (PB) oriented handmade enucleation (OHE) group respectively]. After removal of the cumulus cells and partial digestion of the zona pellucida, oocytes with visible extrusion cones and/or polar bodies attached to the surface were subjected to oriented bisection. Putative cytoplasts without extrusion cones or PB were selected as recipients. Two cytoplasts were electrofused with one transgenic fibroblasts expressing green fluorescent protein (GFP), while non-transgenic fibroblasts were used as controls. Reconstructed embryos were cultured in Well of Wells (WOWs) with porcine zygote medium 3 (PZM-3) after activation. Cleavage and blastocyst rates were registered on day 2 and day 7 of in vitro culture respectively. Meanwhile, the total blastocyst cell number was counted on day 7. We found that the difference was only observed between blastocyst rates (38.6 ± 2% vs 48.1 ± 3%) of cloned embryos with GFP transgenic fibroblast cells after CAHE vs OHE. With adjusted time-lapse for zonae-free cloned embryos cultured in WOWs with PZM-3, it was obvious that in vitro developmental competence after CAHE was compromised when compared with the OHE method. OHE enucleation method seems to be a potential superior alternative method used for somatic cell nuclear transfer (SCNT) with transgenic fibroblast cells.     

Strong regularities in world wide web surfing

One of the most common modes of accessing information in the World Wide Web is surfing from one document to another along hyperlinks. Several large empirical studies have revealed common patterns of surfing behavior. A model that assumes that users make a sequence of decisions to proceed to another page, continuing as long as the value of the current page exceeds some threshold, yields the probability distribution for the number of pages that a user visits within a given Web site. This model was verified by comparing its predictions with detailed measurements of surfing patterns. The model also explains the observed Zipf-like distributions in page hits observed at Web sites.     

广东省坡地柑桔园有机无机肥料配施的效应研究

在赤红壤发育的旱坡地柑桔园开展不同有机无机肥料配施肥效试验,结果表明,与单施化肥相比,有机肥配施化肥能显著提高柑桔的产量和食用品质,其中沙糖桔增产率为16.3%～18.4%,年桔增产率为7.8%～16.4%。此外,施用有机肥处理能显著提高柑桔园土壤微生物量,在施用等氮量条件下,随着有机肥施用量的增加土壤微生物量碳和氮呈递增趋势,说明施用有机肥对柑桔园土壤微生物量碳和氮有显著的影响。     

Reconstruction of Current Flow and Imaging of Current-Limiting Defects in Polycrystalline Superconducting Films

Magneto-optical imaging was used to visualize the inhomogeneous penetration of magnetic flux into polycrystalline TlBa2Ca2Cu3Ox films with high critical current densities, to reconstruct the local two-dimensional supercurrent flow patterns and to correlate inhomogeneities in this flow with the local crystallographic misorientation. The films have almost perfect c-axis alignment and considerable local a- and b-axis texture because the grains tend to form colonies with only slightly misaligned a and b axes. Current flows freely over these low-angle grain boundaries but is strongly reduced at intermittent colony boundaries of high misorientation. The local (<10-micrometer scale) critical current density Jc varies widely, being up to 10 times as great as the transport Jc (scale of approximately 1 millimeter), which itself varies by a factor of about 5 in different sections of the film. The combined experiments show that the magnitude of the transport Jc is largely determined by a few high-angle boundaries.