Vaginal isolation of beta‐haemolytic Streptococcus from bitches with and without neonatal deaths in the litters

The aim of the study was to identify beta‐haemolytic streptococci in the vagina of bitches who had delivered healthy litters and bitches who had delivered litters in which neonatal deaths occurred. Fifty‐one bitches divided into two groups were used. Group 1 (G1) included 28 bitches that had delivered healthy litters and group 2 (G2) included 23 bitches that had delivered puppies who died in the neonatal period. Two vaginal samples were taken, one in proestrus and the other at the end of gestation (EG). Beta‐haemolytic Streptococcus (BS) was isolated from 16 bitches (57%) in G1 and from 21 bitches (91%) in G2. The bacteriological cultures, serological tests (Streptex^®) and PCR assay allowed identification of Streptococcus canis and Streptococcus dysgalactiae in G1 and G2. Ultramicroscopic studies allowed the observation of M Protein and capsules in strains of S. dysgalactiae and S. canis in G1 and G2. The S. canis strains isolated from G2 showed thicker capsules than S. canis strains isolated from G1 (234 ± 24.2 vs 151.23 ± 28.93 nm; p < .001.). No differences were observed in capsule thickness between strains of S. dysgalactiae isolated from G1 and G2 (210 ± 13.54 vs 211.66 ± 19.67 nm; p > .70). All strains of beta‐haemolytic Streptococcus isolated were penicillin sensitive. Penicillin was administered from EG to 5 days post‐partum in 10 G2 females with isolation of BS (G2A). Saline solution was administered in eleven G2 females with isolation of BS (G2B). Ninety per cent of the puppies survived in G2A and 25% survived in G2B. Our results suggest BS is involved in canine neonatal deaths.     

Determining nitrogen status of young loblolly pine by leaf reflectance

Five-year-old lobloliy pine (Pinus taeda L.) seedlings were grown in sand culture in a completely randomized experimental design with eight nitrogen concentrations and three replications. Nitrogen concentration in the nutrient solution varied from 2 to 400 ppm. After a full growing season under treatment, percent reflectance of sunlight by new foliage was determined. Foliar samples were analyzed for nitrogen and chlorophyll. There was a strong positive correlation between nitrogen content and chlorophyll content (r = 0.895). The natural logarithm of percent reflectance was negatively correlated with both percent nitrogen content (r = -0.845) and chlorophyll content (r = -0.838). From these results, prediction equations for estimating nitrogen and chlorophyll content, as a function of reflectance, were formulated by regression analysis.     

10种玉米胚乳突变基因型淀粉糊化的热力学特性

玉米淀粉粝化过程的热力学特性对于淀粉在食品和非食品工业中的利用具有重要意义，本文以近等基因系为材料，采用差热扫描分析仪（ＤＳＣ）研究了ｏｈ４３和Ｂ３７遗传背景的＋／＋；ａｅ／ａｅ；ｄｕ／ｄｕ；ｓｕ２／ｓｕ２；ｗｘ／ｗｘ；ａｅ／ａｅ；ｄｕ／ｄｕ；ａｅ／ａｅ，ｗｘ／ｗｘ；ｄｕ／ｄｕ，ｓｕ２／ｓｕ２；ｄｕ／ｄｕ，ｗｘ／ｗｘ；和ｓｕ２／ｓｕ２ｗｘ／ｗｘ胚乳突变基因型对淀粉糊化的热力学性状的效应。结果表明，