杭州湾、钱塘江流域肉毒梭菌分布调查及其生物学特性的研究

杭州湾、钱塘江流域沿岸外环境的肉毒梭菌分布很广。调查22个点检出阳性21个点。外环境各种样品的总检出率为75.95％,上海地区的检出率最低(29.41％),其它地区间的检出率无显著差异。绍兴市区生产的酱豆面制品肉毒梭菌的检出率为20％。检出的所有菌株几乎均为无毒株,其中2株弱毒株其毒力弱到无法定型。生化试验结果显示,被试大多数菌株的生化特性与A、B、F型的PL株相似,但有13株菌株的个别生化反应与试验菌株的总体不同。     

X-ray-induced specific-locus mutations in the ad-3 region of two-component heterokaryons of Neurospora crassa. II. More extensive genetic tests reveal an unexpectedly high frequency of multiple-locus mutations

More extensive genetic tests have been performed on a series of 832 X-ray-induced specific-locus mutations in the ad-3 region of a 2-component heterokaryon (H-12) of Neurospora crassa, reported earlier (Webber and de Serres 1965). Using a new tester strains and techniques for performing large-scale genetic tests (heterokaryon, dikaryon and trikaryon) to characterize ad-3 mutants induced in 2-component heterokaryons, new data have been obtained on this sample of X-ray-induced ad-3 mutants. These new data show that unexpectedly high frequencies of both single-locus (gene/point) mutations and multilocus deletions in the ad-3 region have additional, but separate, sites of resessive lethal (RL^CL) damage in the immediately adjacent genetic regions. The frequencies of these X-ray-induced multiple-locus mutants in the ad-3 region are orders of magnitude higher than expected on the basis of target theory and classical models of chromosome structure during interphase. Current models of interphase chromosome structure in higher eukaryotes as revealed by chromosome “painting” offer a possible explanation of the Neurospora data.     

Evaluation of a soil test method and plant analysis for determing the sulphur status of alluvial soils

Summary In a pot experiment with soils of Alfisol, Entisol, and Inceptisol orders, the relative yield of Egyptian clover (Trifolium alexandrinum L.) was significantly correlated with Morgan's reagent (N NaOAc+HOAc, pH 4.8)—extractable soil S (r=0.88), plant S (r=0.82), and plant N/S ratio (r=−0.77) suggesting suitability of these tests for diagnosing S deficiency. Total plant S lower than 0.21 per cent, plant N/S ratio wider than 17, and extractable soil S lower than 10 ppm were indicative of S deficiency, and were suggested therefore to be critical limits for these tests. Nitrogen and S in plant proteins were in near constant ratio of 16 and were significantly correlated (r=0.99). Sixty one per cent of 250 surface soil samples had less than 10 ppm extractable S and hence were deficient in S, suggesting a widespread S deficiency in soils under study. Extractable soil S in all soil series was significantly correlated with electrical conductivity and alkaline KMnO₄-extractable N, but not with pH, organic C, and CaCO₃.     

Theoretical value of estimates of general combining ability in the autotetraploid crop

Summary The means of half-sib progenies have been indicated as selection criteria for intra-population improvement while the average of the means of full-sib progenies in diallel analyses have been proposed as predictors, in part, of the means of untested synthetic varieties. When these measures based on progeny means are expressed as deviations from a defined greater population of crosses, they are often termed the general combining ability (GCA). In this study the GCA estimates or a facsimile were theoretically investigated for the one locus, digene, autotetraploid model to verify the genetic basis and its value for selection and prediction in the presence of a naturally occurring phenomena of autopolyploids called gametic disequilibrium with three types of non-additive inheritance. Two breeding objectives were envisioned, the selection of best parents with recurrent selection based on GCA in the continued development of elite populations and the prediction of advanced generation synthetic variety performance. The first generation means of progenies with a potential bias due to gametic disequilibrium were compared to GCA estimation of same progenies in the absence of gametic disequilibrium. The results indicated that testcrossing plants to a population without gametic disequilibrium could be used for selection of best parents. The gametic disequilibrium in the cross may increase or depress selection response dependent on the array of genotypes which happen to be evaluated, on the type of genic action at the locus, and on the frequency of the desirable allele in the testor population. The GCA estimates for prediction of synthetic performance were potentially biased by gametic disequilibrium. An assumption of pollination by the same array of gametes was made for all plants, but obviously was unrealistic for GCA estimation with partial diallels, or with no selfing, and in other situations. The GCA estimate was shown to be an unreliable predictor of synthetic variety performance. When it was assumed that different plants were pollinated by different arrays of gametes, a more realistic situation, no genetic interpretation of GCA values was possible even with purely additive gene action at the locus.Cooperative investigation of the Alfalfa Production Research Unit, United States Department of Agriculture, Agricultural Research Service, and the Nevada Agricultural Experiment Station, Reno, Nevada     

Major outer membrane proteins in the phytopathogenic bacteria Erwinia carotovora subsp. carotovora and subsp. atroseptica

Abstract Immunological similarities of heat-labile Escherichia coli enterotoxins pathogenic for man (LTh) and piglets (LTp) and cholera enterotoxin (CT) were examined quantitatively by the reversed Mancini test. The following results were obtained by analysis of rabbit antisera against these toxins. (1) 86% and 61% of the immunoglobulins in anti-CT antisera were antibodies cross-reacting with LTh and LTp, respectively; (2) 77% and 66% of the immunoglobulins in anti-LTh antisera were antibodies cross-reacting with LTp and CT, respectively; (3) 75% and 59% of the immunoglobulins in anti-LTp antisera were antibodies cross-reacting with LTh and CT, respectively.     

测定呼吸道合胞病毒抗体方法敏感性的比较

用ELISA、间接免疫荧光和中和试验三种方法测定兔免疫血清的呼吸道合胞病毒抗体。结果中和试验测定的免疫血清几何平均抗体滴度为1:32;间接免疫荧光试验为1:508,比中和试验高16倍;ELISA测得的抗体滴度1:4,000～1:5,000,为中和试验的125～156倍。以ELISA敏感性最高,间接免疫荧光试验次之,中和试验景差。