Search results for "Biological variation"
showing 4 items of 14 documents
Regulation of Phenotypic Switching and Heterogeneity in Photorhabdus luminescens Cell Populations.
2019
Phenotypic heterogeneity in bacterial cell populations allows genetically identical organisms to different behavior under similar environmental conditions. The Gram-negative bacterium Photorhabdus luminescens is an excellent organism to study phenotypic heterogeneity since their life cycle involves a symbiotic interaction with soil nematodes as well as a pathogenic association with insect larvae. Phenotypic heterogeneity is highly distinct in P. luminescens. The bacteria exist in two phenotypic forms that differ in various morphologic and phenotypic traits and are therefore distinguished as primary (1°) and secondary (2°) cells. The 1 cells are bioluminescent, pigmented, produce several sec…
Analysis of microbiological variation in PDO Vastedda della valle del Belìce cheese during the storage period
2011
The PDO “Vastedda della valle del Belìce” is a Sicilian pasta filata sheep cheese, made from raw milk without starter addition. It is a small round cheese without rind, weighing about 500-700 g. It is cheese is marketed also out of Sicily to allow its marketing and to prolong its shelf-life. The aim of this work was to evaluate the variation of microbiological parameters during the shelf-life period. Then 162 Vastedda cheeses from 18 cheese-making processes in 7 farms have been analysed at different times of storage at 4°C (0, 15, 30, 45, 60, 75, 90, 105, 120 days). Coliforms and E. coli were detected into 7/18 cheese-making processes and their count decreased during the storage period. Ent…
Intra-individual variability in TSH levels of healthy women during the first half of pregnancy
2017
TSH is the parameter most widely accepted to assess thyroid function, especially in pregnant women. The aim of this current study was to analyze intra-individual changes in TSH during the first half of pregnancy in women with TSH levels higher than 2.5mIU/L in early pregnancy.An observational, prospective study was conducted on 243 healthy pregnant women in the first trimester of pregnancy. Thyroid function was assessed by testing TSH and free T4 levels. A subgroup of women with TSH levels2.5mIU/L underwent additional tests (TSH, free T4, peroxidase antibodies). Information on dietary iodine intake and/or iodine supplements was also recorded.Mean TSH level was 1.89mIU/L (range 0.024-6.48mIU…
Diversity in warning coloration: selective paradox or the norm?
2019
Aposematic theory has historically predicted that predators should select for warning signals to converge on a single form, as a result of frequency-dependent learning. However, widespread variation in warning signals is observed across closely related species, populations and, most problematically for evolutionary biologists, among individuals in the same population. Recent research has yielded an increased awareness of this diversity, challenging the paradigm of signal monomorphy in aposematic animals. Here we provide a comprehensive synthesis of these disparate lines of investigation, identifying within them three broad classes of explanation for variation in aposematic warning signals: …