Transcriptome analysis of Anopheles stephensi embryo using expressed sequence tags.

Germ band retraction (GBR) stage is one of the important stages during insect development. It is associated with an extensive epithelial morphogenesis and may also be pivotal in generation of morphological diversity in insects. Despite its importance, only a handful of studies report the transcriptome repertoire of this stage in insects. Here, we report generation, annotation and analysis of ESTs from the embryonic stage (16–22 h post fertilization) of laboratoryreared Anopheles stephensi mosquitoes. A total of 1002 contigs were obtained upon clustering of 1140 high-quality ESTs, which demonstrates an astonishingly low transcript redundancy (12.1%). Putative functions were assigned only to 213 contigs (21%), comprising mainly of transcripts encoding protein synthesis machinery. Approximately 78% of the transcripts remain uncharacterized, illustrating a lack of sequence information about the genes expressed in the embryonic stages of mosquitoes. This study highlights several novel transcripts, which apart from insect development, may significantly contribute to the essential biological complexity underlying insect viability in adverse environments. Nonetheless, the generated sequence information from this work provides a comprehensive resource for genome annotation, microarray development, phylogenetic analysis and other molecular biology applications in entomology.

Comparative analysis of fecal microflora of healthy full-term Indian infants born with different methods of delivery (vaginal vs cesarean): Acinetobacter sp. prevalence in vaginally born infants.

In this study fecal microflora of human infants born through vaginal delivery (VB) and through cesarean section (CB) were investigated using culture-independent 16S rDNA cloning and sequencing approach. The results obtained clearly revealed that fecal microbiota of VB infants distinctly differ from those in their counterpart CB infants. The intestinal microbiota of infants delivered by cesarean section appears to be more diverse, in terms of bacteria species, than the microbiota of vaginally delivered infants. The most abundant bacterial species present in VB infants were Acinetobacter sp., Bifidobacterium sp. and Staphylococcus sp. However, CB infant’s fecal microbiota was dominated with Citrobacter sp., Escherichia coli and Clostridium difficile. The intestinal microbiota of cesarean section delivered infants in this study was also characterized by an absence of Bifidobacteria species. An interesting finding of our study was recovery of large number of Acinetobacter sp. consisting of Acinetobacter pittii (former Acinetobacter genomic species 3), Acinetobacter junii and Acinetobacter baumannii in the VB infants clone library. Among these, Acinetobacter baumannii is a known nosocomial pathogen and Acinetobacter pittii (genomic species 3) is recently recognized as clinically important taxa within the Acinetobacter calcoaceticus–Acinetobacter baumannii (ACB) complex. Although none of the infants had shown any sign of clinical symptoms of disease, this observation warrants a closer look.

Molecular analysis of gut microbiota in obesity among Indian individuals.

Obesity is a consequence of a complex interplay between the host genome and the prevalent obesogenic factors among the modern communities. The role of gut microbiota in the pathogenesis of the disorder was recently discovered; however, 16S-rRNA-based surveys revealed compelling but community-specific data. Considering this, despite unique diets, dietary habits and an uprising trend in obesity, the Indian counterparts are poorly studied. Here, we report a comparative analysis and quantification of dominant gut microbiota of lean, normal, obese and surgically treated obese individuals of Indian origin. Representative gut microbial diversity was assessed by sequencing fecal 16S rRNA libraries for each group (n=5) with a total of over 3000 sequences. We detected no evident trend in the distribution of the predominant bacterial phyla, Bacteroidetes and Firmicutes. At the genus level, the bacteria of genus Bacteroides were prominent among the obese individuals, which was further confirmed by qPCR (P<0.05). In addition, a remarkably high archaeal density with elevated fecal SCFA levels was also noted in the obese group. On the contrary, the treated-obese individuals exhibited comparatively reduced Bacteroides and archaeal counts along with reduced fecal SCFAs. In conclusion, the study successfully identified a representative microbial diversity in the Indian subjects and demonstrated the prominence of certain bacterial groups in obese individuals; nevertheless, further studies are essential to understand their role in obesity.

Molecular typing of fecal eukaryotic microbiota of human infants and their respective mothers.

The micro-eukaryotic diversity from the human gut was investigated using universal primers directed towards 18S rRNA gene, fecal samples being the source of DNA. The subjects in this study included two breast-fed and two formula-milk-fed infants and their mothers. The study revealed that the infants did not seem to harbour any microeukaryotes in their gut. In contrast, there were distinct eukaryotic microbiota present in the mothers. The investigation is the first of its kind in the comparative study of the human feces to reveal the presence of micro-eukaryotic diversity variance in infants and adults from the Indian subcontinent. The micro-eukaryotes encountered during the investigation include known gut colonizers like Blastocystis and some fungi species. Some of these micro-eukaryotes have been speculated to be involved in clinical manifestations of various diseases. The study is an attempt to highlight the importance of micro-eukaryotes in the human gut.

Wolbachia and termite association: present status and future implications.

Inherited symbionts play an important role in the ecology and evolution of many species. One such inherited symbiont, Wolbachia, is known to have many interesting and diverse symbiotic associations with its arthropod and nematode hosts, ranging from parasitism to mutualism (Werren et al. 2008). The organism is notable for signifi cantly altering the reproductive capabilities of its arthropod hosts and manipulating their cell biology by inducing different phenotypes such as male killing, feminization, parthenogenesis, cytoplasmic incompatibility (sperm–egg incompatibility) and even speciation in certain species (Werren et al. 2008). These interactions become more interesting due to the spatial variation and phenotype of Wolbachia strains. Wolbachia strains that are genotypically very closely related can induce diverse phenotypic effects in different hosts, whereas different strains can induce similar phenotypic effects in the same hosts (Jiggins et al. 2002). Therefore, characterization of the Wolbachia genotype and its phenotypic effect in different hosts is important for understanding the ecology and evolution of different species. Since Wolbachia cannot be cultured outside host cells, traditional microbiological methods cannot be applied to study these bacteria. Currently, they are categorized into eleven different ‘supergroups’ (labelled alphabetically A–K) on the basis of clades formed in gene phylogenies (Lo et al. 2002; Bordenstein and Rosengaus 2005; Casiraghi et al. 2005; Ros et al. 2009). Termites are a group of social insects usually classifi ed in the taxonomic rank of order Isoptera, and described as ‘ecosystem engineers’ due to their important role in providing soil ecosystem services. They are major detrivores, particularly in the subtropical and tropical regions, and their recycling of wood and other plant matter is of considerable ecological importance (Harris 1971). Their ancient origin (Devonian period), great diversity and considerable ecological, biological and behavioural plasticity suggests that characterization of Wolbachia in this group is needed in order to understand the impact of the symbiont on termite reproduction, evolution and speciation (Roy and Harry 2007). The phenotypic effects of Wolbachia in Isoptera are still unknown but molecular data concerning these termite symbionts have recently become available. The available literature suggests the occurrence of Wolbachia in termite families Termopsidae, Kalotermitidae, Serritermitidae, Rhinotermitidae and Termitidae. Four phylogenetically different Wolbachia supergroups have been reported in termites. Twenty termite species have been reported to harbour Wolbachia. Out of these, thirteen species (Kalotermes fl avicollis, Coptotermes lacteus, Coptotermes acinaciformis, Cryptotermes secundus, Heterotermes sp., Nasutitermes takasagoensis, Nasutitermes sp., Nasutitermes nigriceps, Hospitalitermes mediofl avus, Microcerotermes sp., Apilitermes longiceps, Labiotermes labralis, Microtermes sp.) have supergroup F Wolbachia infection (Casiraghi et al. 2005; Lo et al. 2002; Lo and Evans 2007; Roy and Harry 2007). Two Zootermopsis species (Zootermopsis nevadensis and Zootermopsis angusticollis) carry supergroup H Wolbachia (Bordenstein and Rosengaus 2005). Cubitermes sp. affi nis subarquatus harbour diverse types of Wolbachia belonging to the supergroup A and B clade (Roy and Harry 2007), Incisitermes snyderi carry supergroup A Wolbachia (Baldo et al. 2006), while Wolbachia from Serritermes serrifer, Neotermes luykxi and Neotermes jouteli belong to a divergent sister clade within supergroup A (Lo and Evans 2007). Termites, like other groups of arthropods, can tolerate Wolbachia of more than one supergroup, although individual species can harbour only single infections. This provides some evidence for the horizontal transmission of Wolbachia. Infection with different Wolbachia supergroups in various termite species can be parsimoniously explained by independent acquisition of these lineages in termites, rather than a single ancient ancestral infection, with subsequent divergence and/or widespread loss (Bordenstein and Rosengaus 2005).