Protease-mediated prophenoloxidase activation in the haemolymph of American cockroach Periplaneta americana

Prophenoloxidase has been successfully obtained from the haemolymph of the cockroach Periplaneta americana using cane sugar saline solution. The proenzyme was activated by various exogenously added proteases such as chymotrypsin, trypsin, subtilisin and thermolysin. Thermolysin was found to be the greatest activator, followed by chymotrypsin and subtilisin. Chymotrypsin activation showed a lag period when compared with the other proteases tested, indicating that activation by chymotrypsin followed an indirect path, whereas, subtilisin and thermolysin activated the proenzyme directly.Exogenously added protease inhibitor showed inhibition towards protease-mediated prophenoloxidase activation. Benzamidine inhibited chymotrypsin and trypsin activation, whereas soybean trypsin inhibitor inhibited trypsin. In situ inhibitor isolated from the haemocytes of Periplaneta americana inhibited the prophenoloxidase activation and showed evidence for the presence of a built-in inhibition system for the release of the components of the prophenoloxidase activating system of P. americana. Electrophoretic localization of activated phenoloxidase showed two bands, suggesting the dimeric condition of high mol. wt prophenoloxidase.     

Latent larval cuticular phenoloxidase in the coconut pest,Oryctes rhinoceros

Cuticular phenoloxidase (Tyrosinase) in the larval stage of the coconut pest Oryctes rhinoceros has been extracted in the stable proform using cane sugar saline/borate buffer. The extracted prophenol oxidase can be activated by the addition of proteolytic enzymes such as trypsin, chymotrypsin, thermolysin, and subtilisin. Detergents such as SDS and Tween-80 also activated the enzyme. Electrophoretical analysis revealed dissociation of the enzyme into two molecular forms after its activation by proteolytic enzymes. The functional significance of the enzyme is suggested to involve the generation of quinone compounds in the wound healing process: most phenoloxidase inhibitors prevented melanization when applied topically to surgical wounds. © 1996 Wiley-Liss, Inc.     

Genotype–phenotype correlation in long QT syndrome families

Heterogeneity in clinical manifestations is a well-known feature in Long QT Syndrome (LQTS). The extent of this phenomenon became evident in families wherein both symptomatic and asymptomatic family members are reported. The study hence warrants genetic testing and/or screening of family members of LQTS probands for risk stratification and prediction.Of the 46 families screened, 18 probands revealed novel variations/compound heterozygosity in the gene/s screened. Families 1–4 revealed probands carrying novel variations in KCNQ1 gene along with compound heterozygosity of risk genotypes of the SCN5A, KCNE1 and NPPA gene/s polymorphisms screened. It was also observed that families- 5, 6 and 7 were typical cases of “anticipation” in which both mother and child were diagnosed with congenital LQTS (cLQTS). Families- 16 and 17 represented aLQTS probands with variations in IKs and INa encoding genes. First degree relatives (FDRs) carrying the same haplotype as the proband were also identified which may help in predictive testing and management of LQTS. Most of the probands exhibiting a family history were found to be genetic compounds which clearly points to the role of cardiac genes and their modifiers in a recessive fashion in LQTS manifestation.     

Population genetic structure in Indian Austroasiatic speakers: the role of landscape barriers and sex-specific admixture

The geographic origin and time of dispersal of Austroasiatic (AA) speakers, presently settled in south and southeast Asia, remains disputed. Two rival hypotheses, both assuming a demic component to the language dispersal, have been proposed. The first of these places the origin of Austroasiatic speakers in southeast Asia with a later dispersal to south Asia during the Neolithic, whereas the second hypothesis advocates pre-Neolithic origins and dispersal of this language family from south Asia. To test the two alternative models, this study combines the analysis of uniparentally inherited markers with 610,000 common single nucleotide polymorphism loci from the nuclear genome. Indian AA speakers have high frequencies of Y chromosome haplogroup O2a; our results show that this haplogroup has significantly higher diversity and coalescent time (17-28 thousand years ago) in southeast Asia, strongly supporting the first of the two hypotheses. Nevertheless, the results of principal component and "structure-like" analyses on autosomal loci also show that the population history of AA speakers in India is more complex, being characterized by two ancestral components-one represented in the pattern of Y chromosomal and EDAR results and the other by mitochondrial DNA diversity and genomic structure. We propose that AA speakers in India today are derived from dispersal from southeast Asia, followed by extensive sex-specific admixture with local Indian populations.     

Electroantennogram and flight orientation response of Cotesia plutellae to hexane extract of cruciferous host plants and larvae of Plutella xylostella

The braconid wasp Cotesia plutellae is an important larval parasitoid of the diamondback moth (DBM) Plutella xylostella, which a major pest of crucifers in the tropics and subtropics. The peripheral olfactory responses of antennal chemoreceptors of C. plutellae to various cruciferous host plants of DBM and host larval body (cuticle) extracts were examined by electroantennogram (EAG) detection and the behavioral response to a concentration of 1% was analyzed in a Y‐tube olfactometer. Females of C. plutellae exhibited dose‐dependant EAG response for all the extracts tested. Antennal stimulation with 0.1 and 1% concentrations elicited stronger EAG responses than lower concentrations for all the extracts. Host plant extracts were more stimulatory to virgin females, while gravid females exhibited increased antennal sensitivity to host larval body extract odors. In the flight orientation studies, virgin females exhibited increased orientation toward host plant extracts, while gravid females oriented more toward host larval body odors. The EAG response profile and the corresponding orientation behavior revealed a differential preference by the parasitoid wasp to host plant and host‐related cues. Mustard and cauliflower extracts were more attractive to females than other extracts. The possible behavioral manipulation of this specialist parasitoid using these extracts for effective biological control of diamondback moth is discussed.     

Mitochondrial DNA variations associated with recurrent pregnancy loss among Indian women

Several genetic factors have been found to be associated with recurrent pregnancy loss (RPL). However, not many attempts have been made to associate the mitochondrial DNA (mtDNA) variations with RPL. Therefore, we have analyzed the complete mtDNA of 100 women with RPL and 12 aborted fetal tissues. Our analysis revealed a total of 681 variations, most of which were in NADH Dehydrogenase (ND) genes that encode mitochondrial enzyme Complex I. Presence of T4216C variation (ND1 gene) in 9% of the RPL women and several pathogenic, and novel mutations suggest the role of mtDNA variations in RPL.     

Shared and unique components of human population structure and genome-wide signals of positive selection in South Asia

South Asia harbors one of the highest levels genetic diversity in Eurasia, which could be interpreted as a result of its long-term large effective population size and of admixture during its complex demographic history. In contrast to Pakistani populations, populations of Indian origin have been underrepresented in previous genomic scans of positive selection and population structure. Here we report data for more than 600,000 SNP markers genotyped in 142 samples from 30 ethnic groups in India. Combining our results with other available genome-wide data, we show that Indian populations are characterized by two major ancestry components, one of which is spread at comparable frequency and haplotype diversity in populations of South and West Asia and the Caucasus. The second component is more restricted to South Asia and accounts for more than 50% of the ancestry in Indian populations. Haplotype diversity associated with these South Asian ancestry components is significantly higher than that of the components dominating the West Eurasian ancestry palette. Modeling of the observed haplotype diversities suggests that both Indian ancestry components are older than the purported Indo-Aryan invasion 3,500 YBP. Consistent with the results of pairwise genetic distances among world regions, Indians share more ancestry signals with West than with East Eurasians. However, compared to Pakistani populations, a higher proportion of their genes show regionally specific signals of high haplotype homozygosity. Among such candidates of positive selection in India are MSTN and DOK5, both of which have potential implications in lipid metabolism and the etiology of type 2 diabetes.     

Indian Siddis: African descendants with Indian admixture

The Siddis (Afro-Indians) are a tribal population whose members live in coastal Karnataka, Gujarat, and in some parts of Andhra Pradesh. Historical records indicate that the Portuguese brought the Siddis to India from Africa about 300-500 years ago; however, there is little information about their more precise ancestral origins. Here, we perform a genome-wide survey to understand the population history of the Siddis. Using hundreds of thousands of autosomal markers, we show that they have inherited ancestry from Africans, Indians, and possibly Europeans (Portuguese). Additionally, analyses of the uniparental (Y-chromosomal and mitochondrial DNA) markers indicate that the Siddis trace their ancestry to Bantu speakers from sub-Saharan Africa. We estimate that the admixture between the African ancestors of the Siddis and neighboring South Asian groups probably occurred in the past eight generations (～200 years ago), consistent with historical records.