Effect of Oil Overlay on Inhibition Potential of Roscovitine in Sheep Cumulus‐Oocyte Complexes

Inhibitors of cyclin‐dependent kinases, as roscovitine, have been used to prevent the spontaneous resumption of meiosis in vitro and to improve the oocyte developmental competence. In this study, the interference of oil overlay on the reversible arrest capacity of roscovitine in sheep oocytes as well as its effects on cumulus expansion was evaluated. For this, cumulus‐oocyte complexes (COCs) were cultured for 20 h in TCM 199 with 10% foetal bovine serum (Control) containing 75 μm roscovitine (Rosco). Subsequently, they were in vitro matured (IVM) for further 18 h in inhibitor‐free medium with LH and FSH. The culture was performed in Petri dishes under mineral oil (+) or in 96 well plates without oil overlay (?) at 38.5°C and 5% CO₂. At 20 and 38 h, the cumulus expansion and nuclear maturation were evaluated under stereomicroscope and by Hoechst 33342 staining, respectively. No group presented cumulus expansion at 20 h. After additional culture with gonadotrophins, a significant rate of COCs from both Control groups (+/?) exhibited total expansion while in both Rosco groups (+/?) the partial expansion prevailed. Among the oocytes treated with roscovitine, 65.2% were kept at GV in the absence of oil overlay while 40.6% of them reached MII under oil cover (p < 0.05). This meiotic arrest was reversible, and proper meiosis progression also occurred in the Control groups (+/?). So, the culture system without oil overlay improved the meiotic inhibition promoted by roscovitine without affecting the cumulus expansion rate or the subsequent meiosis progression.     

Microtechnique for quantitative platelet isolation from blood enabling electronic counting and sizing of animal and human platelets

A technique for rapidly separating platelets from small quantities of whole blood is described. The isolation method allowed for counting and sizing platelets by electronic means, and counts with this new method were closely correlated with those obtained by phase microscopy. Platelet sizing was possible because of the inert and isotonic nature of the density-gradient medium used in the procedure. The technique was applicable to samples of blood from persons, horses, cattle, sheep, goats, pigs, dogs, mice, rats, guinea pigs, and rabbits. The isolation of platelets from whole blood of various species of animals was necessary for electronic counting because of the great variation in sizes of platelets and erythrocytes and the variable sedimentation properties of animal blood.     

Effects of season on the maintenance requirements of mature beef cows

Sixty mature, nonpregnant, nonlactating beef cows of two breed types, Angus and Simmental, were used in a four-period, split-plot study to determine the effects of season on maintenance requirements. Periods were chosen to represent each of the four seasons and ran consecutively from June 14, 1986 through June 20, 1987. All cows were fed at one of four feeding levels (75, 87.5, 112.5, and 125% of estimated ME required for maintenance) a cottonseed hull-based diet in each of the four seasons and were rotated such that all cows received all feeding levels during the study. Retained energy for all cows within periods was determined through changes in body composition determined initially and at the end of each period. Mean DM digestibility (DMD) was similar for both breeds (54.4%), and in both breeds DMD was similar in the summer, fall, and spring and lower (P less than .05) in the winter. Mean DE was 61.4% and also was similar between breeds. Season affected DE, which was greatest (P less than .05) for both breeds in the fall (62.5%). Simmental cows had a 16.1% greater (P less than .05) overall daily ME requirement for weight maintenance than Angus cows (123.5 vs 103.6 kcal/kg.75), and both breeds had greater (P less than .05) requirements during the summer and lower (P less than .05) requirements during the winter (122.6 vs 91.4 and 145.9 vs 109.3 kcal/kg.75 for Angus and Simmental cows, respectively).(ABSTRACT TRUNCATED AT 250 WORDS)     

Factor XII and partial prekallikrein deficiencies in a dog with recurrent gastrointestinal hemorrhage

Factor XII deficiency and impaired prekallikrein activity were diagnosed in a 1-year-old Chinese Shar Pei. The dog experienced repeated episodes of intestinal hemorrhage and diarrhea. Laboratory findings were compatible with blood loss (iron deficiency anemia and hypoproteinemia). Necropsy findings suggested mild infiltrative bowel disease that could have been responsible for the dog's diarrhea, but no explanation for the severe recurrent gastrointestinal hemorrhage could be found. Factor XII deficiency is uncommon in the dog and is not associated with hemorrhagic tendencies. The factor XII deficiency in this case may have contributed to the gastrointestinal hemorrhage.     

Intestinal malabsorption and cryptosporidiosis in an adult dog

Chronic intestinal cryptosporidiosis was diagnosed as the cause of chronic diarrhea and weight loss in an adult dog without obvious signs of immunosuppression. Results of tests for digestive function suggested that the dog had impaired intestinal absorption or bacterial overgrowth. The nutrient malabsorption might have resulted in or have been caused by the cryptosporidiosis. Temporary clinical improvement without reduction in fecal oocyst concentration was noticed following treatment with clindamycin. The dog was euthanatized. At necropsy, the dog was found to have chronic lymphoplasmacytic enteritis and cryptosporidiosis. A veterinary student that worked in the ward where the dog was kept developed cryptosporidal diarrhea.     

TILLING and Ecotilling the Plant Kingdom

The modem crop scientist has a large amount of available nucleotide sequence information to identify genes of potential agronomic importance. Using reverse genetic approaches, specific genes can be disrupted, and hypotheses regarding gene function directly tested in vivo. Although a number of reverse genetic methods have been introduced, many are limited in application because they are organism-specific, expensive, transgenic, or only transiently disrupt gene function. However, traditional mutagenesis using chemical mutagens has been widely used as a forward genetics strategy to create many new crop plant varieties at relatively low cost. Mutagens such as ethyl methanesulphonate （EMS） cause stable point mutations and thus produce an allelic series of truncation and missense changes that can provide a range of phenotypes （Greene et al., 2003）. TILLING （targeting induced local lesions IN genomes） is a high-throughput reverse genetic strategy that combines traditional mutagenesis and SNP discovery methods （Colbert et al., 2001; McCallum et al., 2000）. To identify mutations, target regions of-l.5 kb are amplified with fluorescently labeled gene specific primers. Heteroduplexes are then formed between wild-type and mutant strands, mismatches are cleaved by incubation with a single-strand specific nuclease,     

Mass spectral investigations on trichothecene mycotoxins. II. Detection and quantitation of macrocyclic trichothecenes by gas chromatography/negative ion chemical ionization mass spectrometry

A general, sensitive gas chromatographic/negative ion chemical ionization mass spectrometric (GC/NICIMS) method of analysis was developed for the detection and quantitation of several polar, thermally labile, toxic macrocyclic trichothecenes. The procedure involves the conversion of the molecules to their corresponding alcohols (verrucarols) by alkaline hydrolysis, followed by derivatization of the hydrolysate with heptafluorobutyrylimidazole and analysis by GC/MS technique under negative ion chemical ionization conditions. Nanogram (250 ng) quantities of several macrocyclic trichothecenes with different verrucarol and ester moieties were analyzed successfully with good precision by this procedure. The method was applicable for the accurate determination of at least low ppb levels of these macrocyclic trichothecenes in environmental samples, such as fungal products, fermentation broths, and plant samples. This is the first reported, well developed, sensitive, and applicable method for the detection and quantitation of these compounds in naturally occurring samples.     

Conducting organic materials

Some of the current directions of scientific research on electrically conducting organic solids are reviewed. Both molecular charge transfer salts and polymers are included, with emphasis on the present level of understanding of the novel solid-state properties of these materials in terms of their chemistry and structure. For the charge transfer salts the various types of metal-to-insulator phase transitions which dominate the properties of most of these materials are discussed. Also described are the superconducting and magnetic states which have been found recently. In the case of the polymers the chemistry and physics of the conduction mechanism is examined and contrasted with that of their classical inorganic counterparts.