Possible Origin of Clostridium botulinum Contamination of Eskimo Foods in Northwestern Alaska

Soils from beaches in northwestern Alaska have been found to contain Clostridium botulinum type E, providing evidence of one environmental source of food contamination.     

Some Observations on the Characteristics and Distribution of Adenosine Triphosphatases in Young Roots of Pisum sativum, Cultivar Alaska

A study has been made of some characteristics of ATPases fromyoung pea roots and these enzymes have been shown to differfrom ß glycerophosphatases in several respects. DEAEchromotography and gel electrophoresis have confirmed the existenceof a number of different phosphatases with differing affinitiesfor ATP and sodium ß glycerophosphate. At least twoATP-specific phosphatases have been detected and these accountfor about 57 per cent of the total ATPase activity in pea roots. The distribution of ATPase activity along the axis of the roothas been determined by biochemical assay of serial sectionsand by histochemical methods. It is shown that ATPase activityhas a quite different distribution from ß glycero-phosphataseactivity, thus confirming the separate identity of the two enzymesystems. The distribution of ATPases is discussed in relation to theirpossible role in ion transport.     

Ultrastructural Observations on the Origin and Differentiation of Somatic Cells during Gonadal Development in the Frog Rana nigromaculata

The process of gonad development in the frog Rana nigromaculata was observed using the electron microscope. The gonadal medulla was formed by the proliferation and displacement of the epithelial cells within the primordial gonad, and a distinct continuity was observed between the cortical and medullary cells. Sex differentiation of the gonad occurred directly from the sexually indifferent primordial gonads. In the rudimentary testes, the continuity between the cortical and medullary regions increased closer, and the intermingling of cortical and medullary cells was evident. The inner region of the cortex developed into a cord-like structure and subsequently differentiated into rudimentary seminiferous tubules. The medulla differentiated into the testicular rete and efferent duct. In the rudimentary ovaries, the cortex and medulla were separated and the ovarian cavity was formed in the medullary region. In the cortex, the cortical cells surrounding oocytes which had reached the diplotene stage, differentiated into follicular cells. The intrusion of mesenchymal or blastemal cells derived from extragonadal regions into the cortex or medulla was never observed. These findings do not support Witschi's cortico-medullary antagonistic theory of sex differentiation.     

毛蚶中肠道病毒检测方法的建立

本文建立了检测毛蚶中肠道病毒的方法。病毒在pH4.5时吸附于毛蚶组织,离心后用pH9.5甘氨酸盐水将病毒从毛蚶组织中洗脱出来,并用0.0005mol/L三氯化铝代替Johnson法中的Cat—Floc,达到去除细胞毒性物质的目的。经过再一次离心,利用牛肉浸膏在pH3.5—4.0时凝聚并吸附病毒的特性使洗脱液中的病毒得到浓缩。离心后沉淀溶解于0.1mol/L磷酸氢二钠溶液。用本法提取毛蚶中脊髓灰质炎病毒,当病毒含量为每克组织3.5×10~5至35PFU时,平均回收率为71.2％。     

Genotyping of Cryptosporidium Isolates from Chamelea gallina Clams in Italy

Chamelea gallina clams collected from the mouths of rivers along the Adriatic Sea (central Italy) were found to harbor Cryptosporidium parvum (genotype 2), which is the lineage involved in zoonotic transmission. The clams were collected from the mouths of rivers near whose banks ruminants are brought to graze. This paper reports the environmental spread of C. parvum in Italy and highlights the fact that genotyping of seaborne Cryptosporidium isolates is a powerful tool with which to investigate the transmission patterns and epidemiology of this microorganism.     

Neutral and Nonneutral Mitochondrial Genetic Variation in Deep-Sea Clams from the Family Vesicomyidae

Nucleotide sequences at two mitochondrial genes from 57 individuals representing eight species of deep-sea clams (Vesicomyidae) were examined for variation consistent with the neutral model of molecular evolution. One gene, cytochrome oxidase subunit I (COI), deviated from the expectations of neutrality by containing an excess of intraspecific nonsynonymous polymorphism. Additionally, one species, Calyptogena kilmeri, showed a significant excess of rare polymorphism specifically at the COI locus. In contrast, a second mitochondrial gene, the large-subunit 16S ribosomal RNA gene (16S), showed little deviation from neutrality either between or within species. Together, COI and 16S show no deviation from neutral expectations by the HKA test, produce congruent phylogenetic relationships between species, and show correlated numbers of fixed differences between species and polymorphism within species. These patterns of both neutral and nonneutral evolution within the mitochondrial genome are most consistent with a model where intraspecific nonsynonymous polymorphism at COI is near neutrality. In addition to examining the forces of molecular evolution, we extend hypotheses about interspecific relationships within this family for geographical locations previously unexamined by molecular methods including habitats near the Middle Atlantic, the Aleutian Trench, and Costa Rica. Received: 10 March 1999 / Accepted: 13 September 1999