Antihyperglycemic and antihyperlipidemic activities of wild musk melon (Cucumis melo var. agrestis) in streptozotocin-nicotinamide induced diabetic rats.

Objective: Wild musk melon (Cucumis melo var. agrestis, CMA) is one of the edible plants form Tamil Nadu. Traditionally, this plant was used as diabetic diet (leaves of CMA with Momordica charantia leaves), but there is no scientific report on antidiabetic action of this plant material. Hence, the current research work was designed to evaluate the antihyperglycemic and antihyperlipidemic effect of hydroalcoholic extract of CMA leaves (HALEC) in streptozotocin (STZ)-nicotinamide (NIC)-induced diabetic rats. Methods: Diabetes was induced by administration of STZ (60 mg/kg, i.p.) after 15 min of NIC (120 mg/kg i.p.) administration. The diabetic rats were treated with HALEC (300 and 600 mg/kg, p.o., respectively) for 21 d. Results: After the management with HALEC, blood glucose, HbA1c levels, total cholesterol, LDL cholesterol, triglycerides levels, glycogen phosphorylase and glucose-6-phosphatase levels were significantly diminished in diabetic rats. However, haemoglobin level, HDL cholesterol, liver glycogen, total protein, hexokinase, glucose-6-phosphate dehydrogenase levels were significantly increased in HALEC treated diabetic rats. The histopathological studies of the pancreas in HALEC-treated diabetic rats showed almost normal appearance. L6 cell line study revealed the increased glucose uptake activity of HALEC. High performance thin layer chromatography (HPTLC) analysis confirms the presence of active principles such as rutin, gallic acid and quercetin in HALEC. Conclusion: The results indicated that HALEC possess significant antihyperglycemic and antihyperlipidemic activity in STZ-NIC-induced type II diabetic rats with protective effect. This research work will be useful for the isolation of active principles and development of herbal formulation in phytopharmaceuticals.

Translocations used to generate chromosome segment duplications in Neurospora can disrupt genes and create novel open reading frames.

In Neurospora crassa, crosses between normal sequence strains and strains bearing some translocations can yield progeny bearing a duplication (Dp) of the translocated chromosome segment. Here, 30 breakpoint junction sequences of 12 Dp-generating translocations were determined. The breakpoints disrupted 13 genes (including predicted genes), and created 10 novel open reading frames. Insertion of sequences from LG III into LG I as translocation T(UK8-18) disrupts the eat-3 gene, which is the ortholog of the Podospora anserine gene ami1. Since ami1-homozygous Podospora crosses were reported to increase the frequency of repeat-induced point mutation (RIP), we performed crosses homozygous for a deficiency in eat-3 to test for a corresponding increase in RIP frequency. However, our results suggested that, unlike in Podospora, the eat-3 gene might be essential for ascus development in Neurospora. Duplication-heterozygous crosses are generally barren in Neurospora; however, by using molecular probes developed in this study, we could identify Dp segregants from two different translocation-heterozygous crosses, and using these we found that the barren phenotype of at least some duplication-heterozygous crosses was incompletely penetrant.

Neurospora crassa fmf-1 encodes the homologue of the Schizosaccharomyces pombe Ste11p regulator of sexual development.

The Neurospora crassa fmf-1 mutation exerts an unusual 'perithecium-dominant' developmental arrest; fmf-1 x fmf-1+ cross becomes arrested in perithecial development regardless of whether the mutant participates in the cross as the male or female parent. We localized fmf-1 to the LG IL genome segment between the centromere-proximal breakpoint of the chromosome segment duplication Dp(IL)39311 and the centromere. By mapping crossovers with respect to RFLP markers in this region we further localized fmf-1 to an approximately 34-kb-genome segment. Partial sequencing of this segment revealed a point mutation in the gene NCU 09387.1, a homologue of the Schizosaccharomyces pombe ste11+ regulator of sexual development. The fmf-1 mutation did not complement a NCU 09387.1 deletion mutation, and transformation with wild-type NCU 09387.1 complemented fmf-1. S. pombe Ste11 protein (Ste11p) is a transcription factor required for sexual differentiation and for the expression of genes required for mating pheromone signalling in matP and matM cells. If FMF-1 also plays a corresponding role in mating pheromone signalling in Neurospora, then protoperithecia in an fmf-1 x fmf-1+ cross would be unable to either send or receive sexual differentiation signals and thus become arrested in development.

Chromosome segment duplications in Neurospora crassa: barren crosses beget fertile science.

Studies on Neurospora chromosome segment duplications (Dps) performed since the publication of Perkins's comprehensive review in 1997 form the focus of this article. We present a brief summary of Perkins's seminal work on chromosome rearrangements, specifically, the identification of insertional and quasiterminal translocations that can segregate Dp progeny when crossed with normal sequence strains (i.e., T x N). We describe the genome defense process called meiotic silencing by unpaired DNA that renders Dp-heterozygous crosses (i.e., Dp x N) barren, which provides a basis for identifying Dps, and discuss whether other processes also might contribute to the barren phenotype of Dp x N and Dp x Dp crosses. We then turn to studies suggesting that large Dps (i.e., >300 kbp) can allow smaller gene-sized duplications to escape another genome defense process called repeat-induced point mutation (RIP), possibly by titration of the RIP machinery. Finally, we assess whether in natural populations dominant RIP suppressor Dps provide an "RIP-free" niche for evolution of new genes following the duplication of existing genes.

Genomic sequence of physalis mottle virus and its evolutionary relationship with other tymoviruses.

The genome of physalis mottle tymovirus (PhMV) is 6673 nucleotides long and is rich in cytosine residues (40.58%) like other tymoviruses. The organization of the genes is also similar to that of five other tymoviruses whose sequences are known. However, PhMV has the longest 3' noncoding region as well as the longest replicase (RP) ORF. The RP sequences are similar to those of other tymoviruses (48-60% identity) whereas the coat proteins (CP) and the overlapping proteins (OP) are conserved to a lesser extent (30-50% and 26-34% respectively). A tetra peptide "GILG" was found to be present in all the tymoviral OPs. The PhMV RP also possesses the methyl transferase, polymerase and the helicase motifs found in all the Sindbis-like super group of plant viruses. A phylogenetic analysis of the six tymoviral sequences revealed that they do not have a rigid hierarchical similarity relationship.