Microevolution of <i>Candida albicans</i>Isolate from a Patient with Mucocutaneous Candidiasis and HIV Infection

Candidiasis is the most common opportunistic fungal infection in HIV patients, and its presence is ascribed mainly to the persistence of the original infecting strain. The latter might acquire genetic variations during interaction with the host, reflecting the adaptation of the strain. Here, we report the case of a 32-year-old man complaining of asthenia, irregular hyperpyrexia, and dry cough, who was admitted to the emergency unit. Laboratory examination showed positivity for HIV. Dark violet macular lesions and ulcerated lesions with verrucous erosion were observed at the tip of the nose, whereas an ulcer without exudates was noted in the pubic region. Candida albicans was recovered from the skin by scraping these lesions. Cultures from the bronchoalveolar lavage (BAL) were negative for bacteria and opportunistic fungi but were positive for Candida albicans. The isolates from the skin and BAL were typed by PCR-RFLP and Candida albicans was identified. Analysis by microsatellite length polymorphisms, established that the pubic isolate was a genetic variant of the isolate from the nose and mouth. This suggested a microevolutionary event. Despite clinical support, the patient died of multiple organ failure.

Clonal distribution and possible micro evolution of methicillin-resistant Staphylococcus aureus strains in a teaching hospital in Malaysia

Objective:To genotypically characterize methicillin-resistant Staphylococcus aureus(MRSA)strains isolated from medical and surgical wards in Universiti Kebangsaan Malaysia Medical Centre(UKMMC)in 2009.Methods:MRSA strains were collected and molecularly typed by pulsed-field gel electrophoresis(PFGE).Results:PFGE typing on 180 MRSA isolated in UKMMC identified 5 pulsotypes(A-E)and 6 singletons,where pulsotypes B and C were suspected to he divergent clones originating from a single ancestor.This study also showed that most MRSA strains were isolated from swab(119 isolates),followed by blood(22 isolates),tracheal aspirate(11isolates)and sputum(10 isolates).On the other hand,urine and bone isolates were less,which were 4 and 1 isolates,respectively.The distribution of different pulsotypes of MRSA among wards suggested that MRSA was communicated in surgical and medical wards in UKMMC,with pulsotype B MRSA as the dominant strain.Besides,it was found that most deceased patients were infected by pulsotype B MRSA,however,no particular pulsotype could be associated with patient age,underlying disease,or ward of admittance.Conclusions:Five pulsotypes of MRSA and 6singletons were identified,with pulsotype B MRSA as the endemic strains circulating in these wards,which is useful in establishment of preventive measures against MRSA transmission.

Differentiation of wild boar and domestic pig populations based on the frequency of chromosomes carrying endogenous retroviruses

Analysis of the frequencies of chromosomes carrying various classes of porcine endogenous retroviruses (PERVs) and combinations of these classes was performed in the swine species Sus scrofa L. by using maps constructed in two principal component coordinates. Four population clusters can be recognized in the maps. Cluster 1 is formed by wild boars,cluster 2 by domestic meat breeds, cluster 3 by meat-and-lard (universal) breeds, and cluster 4 by miniature pigs. The maps indicate that modern domesticated swine meat breeds are the closest to the wild type. Meat-and-lard domestic swine breeds are more distant from wild boars, and miniature pigs are diverged the most. The maps showed that microevolution processes associated with PERV carriership frequency had two basic dimensions, or vectors: the vector of fat deposition variation and the “minus” selection vector (determination of commercial traits). Thus, PERVs may cause variation in pig physiology.

Population genomic analysis reveals distinct demographics and recent adaptation in the black flying fox(Pteropus alecto)

As the only mammalian group capable of powered flight,bats have many unique biological traits.Previous comparative genomic studies in bats have focused on long-term evolution.However,the microevolutionary processes driving recent evolution are largely under-explored.Using resequencing data from 50 black flying foxes(Pteropus alecto),one of the model species for bats,we find that black flying fox has much higher genetic diversity and lower levels of linkage disequilibrium than most of the mammalian species.Demographic inference reveals strong population fluctuations(>100 fold)coinciding with multiple historical events including the last glacial change and Toba super eruption,suggesting that the black flying fox is a very resilient species with strong recovery abilities.While long-term adaptation in the black flying fox is enriched in metabolic genes,recent adaptation in the black flying fox has a unique landscape where recently selected genes are not strongly enriched in any functional category.The demographic history and mode of adaptation suggest that black flying fox might be a well-adapted species with strong evolutionary resilience.Taken together,this study unravels a vibrant landscape of recent evolution for the black flying fox and sheds light on several unique evolutionary processes for bats comparing to other mammalian groups.

How do small birds evolve in response to climate change?Data from the long-term record at La Brea tar pits

Biology textbooks describe the small changes in the beaks of the Galápagos finches as exemplars of how birds evolve in response to environmental changes.However,recent studies of the abundant fossil birds at Rancho La Brea find no evidence of evolutionary responses to the dramatic climate changes of the glacial–interglacial cycle over the past 35000 years:none of the large birds exhibit any change in body size or limb proportions,even during the last glacial maximum approximately 18000–20000 years ago,when the southern California chaparral was replaced by snowy coniferous forests.However,these are all large birds with large ranges and broad habitat preferences,capable of living in many different environments.Perhaps the smaller birds at La Brea,which have smaller home ranges and narrower habitats,might respond to climate more like Galápagos finches.The only 3 common small birds at La Brea are the western meadowlark,the yellow-billed magpie and the raven.In this study,we demonstrate that these birds also show complete stasis over the last glacial–interglacial cycle,with no statistically significant changes between dated pits.Recent research suggests that the small-scale changes over short timescales seen in the Galápagos finches are merely fluctuations around a stable morphology,and rarely lead to long-term accumulation of changes or speciation.Instead,the prevalence of stasis supports the view that long-term directional changes in morphology are quite rare.While directional changes in morphology occur frequently over short(<1 ka)timescales,in the long term such changes only rarely remain stable for long enough to appear in the fossil record.