Trees on networks: resolving statistical patterns of phylogenetic similarities among interacting proteins

Background  

Phylogenies capture the evolutionary ancestry linking extant species. Correlations and similarities among a set of species are mediated by and need to be understood in terms of the phylogenic tree. In a similar way it has been argued that biological networks also induce correlations among sets of interacting genes or their protein products.     

Deciduous enamel defects and caries susceptibility in a prehistoric Ohio population

Clinical studies of the relationship between developmental enamel defects and caries susceptibility have often produced conflicting results. This has been due in part to a failure to distinguish between different types of defects. Studies of this association in prehistoric populations have been rare. The complete deciduous dentitions of 57 subadults from the Libben site, a large Late Woodland cemetery in Ottawa County, Ohio, were selected for analysis. Defects were classified as either hypoplasias (deficiencies in matrix apposition) or hypocalcifications (deficiencies in mineralization) and were graded for severity. The presence or absence of carious lesions was recorded for each tooth. Results indicate a strong positive relationship between hypocalcifications and caries susceptibility. The elevated caries susceptibility of hypocalcified teeth may be related to high levels of magnesium or altered enamel microcrystallite orientation within these teeth. Variations in the frequency of hypocalcifications may partially explain differences in caries rates that have been observed in different prehistoric populations.     

The dysplastic nevus: recognition and management

The recognition of atypical or dysplastic nevomelanocytic nevi potentially provides clinicians with another means of identifying individuals at increased risk for cutaneous malignant melanoma. However, a great deal of controversy still surrounds these lesions, their significance, and the clinical and histologic criteria needed for their diagnosis at present. In general, dysplastic nevi tend to be asymmetrical and larger (greater than 5 mm) than ordinary acquired nevi, have a macular component, irregular and ill-defined borders, and haphazard (variegate) coloration. A clinical diagnosis of dysplastic nevi must be confirmed by histopathology, since not all clinically atypical nevi are dysplastic. While precise histopathologic criteria for dysplastic nevi are lacking, most authorities agree that an abnormal nevomelanocytic proliferative pattern as manifested by increased numbers of basilar melanocytes and/or abnormal junctional nevomelanocytic nesting in the setting of lentiginous epidermal hyperplasia, variable degrees of nevomelanocytic nuclear atypia, and a lymphocytic host response are consistent with a histologic diagnosis of dysplastic nevi. Current data for individuals with dysplastic nevi and a family history of cutaneous malignant melanoma (at least two family members with cutaneous malignant melanoma) indicate a relative risk for cutaneous malignant melanoma about 148 times that of the general population. In comparison, cutaneous malignant melanoma risk seems lower for individuals with familial dysplastic nevi (but without familial cutaneous malignant melanoma) and "sporadic" dysplastic nevi. With respect to progression to melanoma, probably the vast majority of dysplastic nevi remain stable or possibly regress. Management of individuals with histologically confirmed dysplastic nevi involves periodic skin examinations. Regional overview and life-size photography are helpful in following these patients. Patients should also be instructed in the examination of their own skin. While a definite relationship between sun exposure and dysplastic nevi remains unproved, the use of sunscreens and avoidance of unnecessary sun exposure are advised. Examination of family members for atypical melanocytic lesions is also recommended.     

南瓜雌蕊与自花及远缘花粉的相互作用

南瓜柱头表面经去垢剂、蛋白酶及Con A处理后花粉不能萌发或花粉管生长受阻,Con A能专一地与柱头表面结合。柱头块加入培养液可促进花粉萌发。不同的远缘花粉授粉后在雌蕊不同部位受阻。在成熟南瓜雌蕊提取液中检测到血凝活性,凝集素可能参与雌蕊对远缘花粉的抑制。     

The histopathology of experimentally infected hamsters with the Lyme disease spirochete, Borrelia burgdorferi

Seven hamsters, experimentally infected with Borrelia burgdorferi, were examined by both cultural and histological techniques at 1 to 9 months postinfection. Spirochetes were detected in the spleen, kidney, or eye of all animals by culture and in the spleen, kidney, eye, liver, or heart blood of five of seven animals by histological examination. Two animals showed nonspecific hepatic portal lymphocytic infiltration, while five of the hamsters displayed no significant histologic signs of inflammation or granuloma formation in the major organ systems. Synovitis and arthropathy did not occur. All animals showed some degree of follicular lymphoid hyperplasia of the spleen. Spirochetes were predominantly extracellular with a rare organism appearing to be partially within a macrophage.