Synthesis and biological activities of 7-aza rebeccamycin analogues bearing the sugar moiety on the nitrogen of the pyridine ring

The synthesis of a new family of 7-aza-rebeccamycin analogues in which the sugar moiety is attached to the nitrogen of the pyridine ring is described. The capacity of the newly synthesized compounds to bind to DNA and to inhibit topoisomerase I has been evaluated. Their cytotoxicities toward four tumor cell lines, one murine leukemia L1210 and three human tumor cell lines, one prostate carcinoma DU145, one colon carcinoma HT29, and one non-small cell lung carcinoma A549, have been determined. Their abilities to inhibit the checkpoint kinase Chk1 have been evaluated.     

Polarity and temporality of high-resolution y-chromosome distributions in India identify both indigenous and exogenous expansions and reveal minor genetic influence of Central Asian pastoralists

Although considerable cultural impact on social hierarchy and language in South Asia is attributable to the arrival of nomadic Central Asian pastoralists, genetic data (mitochondrial and Y chromosomal) have yielded dramatically conflicting inferences on the genetic origins of tribes and castes of South Asia. We sought to resolve this conflict, using high-resolution data on 69 informative Y-chromosome binary markers and 10 microsatellite markers from a large set of geographically, socially, and linguistically representative ethnic groups of South Asia. We found that the influence of Central Asia on the pre-existing gene pool was minor. The ages of accumulated microsatellite variation in the majority of Indian haplogroups exceed 10,000-15,000 years, which attests to the antiquity of regional differentiation. Therefore, our data do not support models that invoke a pronounced recent genetic input from Central Asia to explain the observed genetic variation in South Asia. R1a1 and R2 haplogroups indicate demographic complexity that is inconsistent with a recent single history. Associated microsatellite analyses of the high-frequency R1a1 haplogroup chromosomes indicate independent recent histories of the Indus Valley and the peninsular Indian region. Our data are also more consistent with a peninsular origin of Dravidian speakers than a source with proximity to the Indus and with significant genetic input resulting from demic diffusion associated with agriculture. Our results underscore the importance of marker ascertainment for distinguishing phylogenetic terminal branches from basal nodes when attributing ancestral composition and temporality to either indigenous or exogenous sources. Our reappraisal indicates that pre-Holocene and Holocene-era--not Indo-European--expansions have shaped the distinctive South Asian Y-chromosome landscape.     

Activity of Bacillus thuringiensis delta-endotoxins against codling moth (Cydia pomonella L.) larvae

Solubilized protoxins of nine Cry1 and one hybrid Cry1 delta-endotoxin from Bacillus thuringiensis were tested for their activity against larvae of the codling moth (Cydia pomonella L). Cry1Da was the most toxic, followed by Cry1Ab, Cry1Ba, and Cry1Ac, while Cry1Aa, Cry1Fa, Cry1Ia, and SN19 were still less active. Cry1Ca and Cry1Cb showed no activity. In vitro trypsin activation increased activity of all eight active delta-endotoxins, and dramatically enhanced toxicity of hybrid SN19, Cry1Aa, Cry1Ac, and Cry1Fa. The differences between toxicity of proteins before and after trypsin digestion suggests that proteolytic activation in the C. pomonella digestive tract plays a critical role for the activity of Cry proteins against this insect.     

Characteristics of strawberry plants propagated by in vitro bioreactor culture and ex vitro propagation method

Reproducible protocol for regeneration of complete plantlets from ‘Bounty’ strawberry (Fragaria ananassa Duch.), using a combination of gelled medium and bioreactor system, has been standardized. Sepals, leaf discs, and petiole halves produced multiple buds and shoots when cultured on semi solid‐gelled medium containing 4 μM thidiazuron (TDZ) for 4 wk followed by transferring in liquid medium containing 2 μM TDZ in a bioreactor system and cultured for another 4 wk. TDZ induced shoot proliferation at 0.1 μM in the bioreactor system but inhibited shoot elongation. TDZ‐induced shoots were elongated and rooted in vitro on gelled medium containing 2 μM zeatin. Such bioreactor‐derived tissue culture (BC) plantlets obtained from sepal explants were grown ex vitro and compared with those propagated by tissue culture on gelled medium (GC) and by conventional runner cuttings (RC), for growth, morphology, anthocyanin content, and antioxidant activity after three growth seasons. The BC and GC plants produced more crowns, runners, leaves, and berries than the RC plants although berry weight per plant did not differ significantly. BC and GC plants produced berries with more anthocyanin contents and antioxidant activities than those produced by the RC plants. However, intersimple sequence repeat (ISSR) marker assay produced a homogenous amplification profile in the tissue culture and donor control plants confirming the clonal fidelity of micropropagated plants. In vitro culture on TDZ and zeatin‐containing nutrient media apparently induced the juvenile branching characteristics that favored enhanced vegetative growth with more crown, runners, leaf, and berry production.     

BMP type II receptor regulates positioning of outflow tract and remodeling of atrioventricular cushion during cardiogenesis

Signaling of bone morphogenetic protein (BMP) via type I and type II receptors is involved in multiple processes contributing to cardiogenesis. To investigate the role of the BMP type II receptor (BMPRII) in heart development, the BMPRII gene was deleted throughout the embryo during gastrulation using a Mox2-Cre transgene. BMPRII^flox/−;Mox2-Cre mice exhibited cardiac defects including double-outlet right ventricle, ventricular septal defect (VSD), atrioventricular (AV) cushion defects, and thickened valve leaflets. To characterize the tissue-specific functions of BMPRII in cardiogenesis, a series of Cre transgenes (αMHC-, Tie2-, Wnt1-, and SM22α-Cre) was employed. Interestingly, myocardial development was normal when the BMPRII gene was deleted in myocardial cells using Mox2-Cre, αMHC-Cre, or SM22α-Cre transgenes, suggesting that signaling by other BMP type II receptors may compensate for the absence of BMPRII in the myocardial cells. AV cushion defects including atrial septal defect, membranous VSD, and thickened valve leaflets were found in BMPRII^flox/−;Tie2-Cre mice. Abnormal positioning of the aorta was observed in BMPRII^flox/−;Wnt1-Cre and BMPRII^flox/−;SM22α-Cre mice. Taken together, these results demonstrate that endocardial BMPRII expression is required for septal formation and valvulogenesis. Moreover, mesenchymal BMPRII expression in the outflow tract cushion is required for proper positioning of the aorta.     

Chemical analysis of an immunostimulating (1→4)-, (1→6)-branched glucan from an edible mushroom, Calocybe indica

An immunostimulating water-soluble glucan was isolated from hot aqueous extract of fruit bodies of an edible mushroom Calocybe indica. Structural investigation of the glucan was carried out using acid hydrolysis, methylation analysis, and NMR studies ((1)H, (13)C, DEPT-135, TOCSY, DQF-COSY, NOESY, ROESY, HMQC, and HMBC). On the basis of above-mentioned experiments, the structure of the repeating unit of the polysaccharide was established as [see figure in text]. This glucan stimulated the splenocytes and thymocytes.     

Plasmodium subtilisin-like protease 1 (SUB1): insights into the active-site structure, specificity and function of a pan-malaria drug target

Release of the malaria merozoite from its host erythrocyte (egress) and invasion of a fresh cell are crucial steps in the life cycle of the malaria pathogen. Subtilisin-like protease 1 (SUB1) is a parasite serine protease implicated in both processes. In the most dangerous human malarial species, Plasmodium falciparum, SUB1 has previously been shown to have several parasite-derived substrates, proteolytic cleavage of which is important both for egress and maturation of the merozoite surface to enable invasion. Here we have used molecular modelling, existing knowledge of SUB1 substrates, and recombinant expression and characterisation of additional Plasmodium SUB1 orthologues, to examine the active site architecture and substrate specificity of P. falciparum SUB1 and its orthologues from the two other major human malaria pathogens Plasmodium vivax and Plasmodium knowlesi, as well as from the rodent malaria species, Plasmodium berghei. Our results reveal a number of unusual features of the SUB1 substrate binding cleft, including a requirement to interact with both prime and non-prime side residues of the substrate recognition motif. Cleavage of conserved parasite substrates is mediated by SUB1 in all parasite species examined, and the importance of this is supported by evidence for species-specific co-evolution of protease and substrates. Two peptidyl alpha-ketoamides based on an authentic PfSUB1 substrate inhibit all SUB1 orthologues examined, with inhibitory potency enhanced by the presence of a carboxyl moiety designed to introduce prime side interactions with the protease. Our findings demonstrate that it should be possible to develop 'pan-reactive' drug-like compounds that inhibit SUB1 in all three major human malaria pathogens, enabling production of broad-spectrum antimalarial drugs targeting SUB1.     

Estimating genetic variability in non-model taxa: a general procedure for discriminating sequence errors from actual variation

Genetic variation is the driving force of evolution and as such is of central interest for biologists. However, inadequate discrimination of errors from true genetic variation could lead to incorrect estimates of gene copy number, population genetic parameters, phylogenetic relationships and the deposition of gene and protein sequences in databases that are not actually present in any organism. Misincorporation errors in multi-template PCR cloning methods, still commonly used for obtaining novel gene sequences in non-model species, are difficult to detect, as no previous information may be available about the number of expected copies of genes belonging to multi-gene families. However, studies employing these techniques rarely describe in any great detail how errors arising in the amplification process were detected and accounted for. Here, we estimated the rate of base misincorporation of a widely-used PCR-cloning method, using a single copy mitochondrial gene from a single individual to minimise variation in the template DNA, as 1.62×10(-3) errors per site, or 9.26×10(-5) per site per duplication. The distribution of errors among sequences closely matched that predicted by a binomial distribution function. The empirically estimated error rate was applied to data, obtained using the same methods, from the Phospholipase A(2) toxin family from the pitviper Ovophis monticola. The distribution of differences detected closely matched the expected distribution of errors and we conclude that, when undertaking gene discovery or assessment of genetic diversity using this error-prone method, it will be informative to empirically determine the rate of base misincorporation.