Vasa deferentia and associated structures of the male Panorpodes kuandianensis (Mecoptera: Panorpodidae).

The male reproductive system may provide significant evidence for the taxonomic and phylogenetic analyses of insects. However, current knowledge of the male reproductive system in Mecoptera is mainly concentrated on the external genitalia, and is rarely involved in the internal reproductive system. Here, we investigated the morphology and the fine structure of the vasa deferentia and associated structures of the male reproductive system of Panorpodes kuandianensis Zhong et al., 2011 (Panorpodidae) using light, scanning, and transmission electron microscopy. The male reproductive system of P. kuandianensis consists of a pair of symmetrical testes with three tubular testicular follicles, two epididymides, two distinctly partitioned vasa deferentia, a pair of mesadenia, one ejaculatory sac, and the external genitalia. A pair of expanded seminal vesicles are modified from the median part of the vasa deferentia, and evolve into secretory organs. The seminal vesicles have elongated cylindrical epithelial cells, which contain abundant secretory materials in the cytoplasm and form a small central lumen, likely serving a secretory function rather than provisionally storing sperm as in most other insects. Alternatively, the sperm are stored temporarily in the epididymis, the greatly coiled portion of the vasa deferentia. The morphology of the male reproductive system supports the close relationships of Panorpidae and Panorpodidae.

An enigmatic new species of Panorpa Linneaus from the Bashan Mountains (Mecoptera, Panorpidae).

A new species of Panorpidae, Panorpabashanicolasp. n., is described and illustrated from the Bashan Mountains in central China. The new species is characterized by the following characters: vertex black, with two pale longitudinal stripes and four pale rounded spots; vein 1A ending before the origin of Rs; meso- and metanotum pale, and the pale color extending to tergum III in V-shape; male epandrium emarginate distally in deep U-shape; hypovalves without basal stalk, completely represented by a pair of short hypovalves, extending to distal third of gonocoxite, with five black stout setae in distal portion; paramere simple, S-shaped; a bundle of long hairs between dorsal and ventral valves of aedeagus; dorsal valves of aedeagus much longer than ventral valves and curved ventrally, with distal portion foot-shaped; female medigynium twice as long as wide, with stout axis extending over one-third its length beyond main plate.

Significant positive correlation between the recombination rate and GC content in the human pseudoautosomal region.

This paper establishes that recombination drives the evolution of GC content in a significant way. Because the human P-arm pseudoautosomal region (PAR1) has been shown to have a high recombination rate, at least 20-fold more frequent than the genomic average of approximately 1 cM/Mb, this region provides an ideal system to study the role of recombination in the evolution of base composition. Nine non-coding regions of PAR1 are analyzed in this study. We have observed a highly significant positive correlation between the recombination rate and GC content (rho = 0.837, p < or = 0.005). Five regions that lie in the distal part of PAR1 are shown to be significantly higher than genomic average divergence. By comparing the intra- and inter-specific AT->GC -GC->AT ratios, we have detected no fixation bias toward GC alleles except for L254915, which has excessive AT-->GC changes in the human lineage. Thus, we conclude that the high GC content of the PAR1 genes better fits the biased gene conversion (BGC) model.

Defective expression of transforming growth factor beta receptor type II is associated with CpG methylated promoter in primary non-small cell lung cancer.

PURPOSE: Reduced expression of the transforming growth factor beta receptor type II (TGF beta RII), a key inhibitor of epithelial cell growth and tumor suppressor gene, was reported frequently in many types of tumors including non-small cell lung cancer (NSCLC). This study explored the significance of the TGF beta RII gene in NSCLC carcinogenesis. EXPERIMENTAL DESIGN: With 43 independent pairs of tumor and paracarcinoma tissue samples from patients with primary NSCLC, we carried out PCR-denaturing gradient gel electrophoresis screening for DNA variants over the coding sequence of the TGF beta RII gene, immunohistochemical assay of TGF beta RII expression, methylation-specific PCR analysis, and semiquantitative reverse transcription-PCR. RESULTS: The PCR-denaturing gradient gel electrophoresis did not detect variation in the whole coding sequence of the TGF beta RII gene, but the immunohistochemistry experiment revealed reduced or lost expression of the gene in 44% (19 of 43) of the tumor samples. The methylation analysis on the 19 pairs detected the frequent occurrence of methylated TGF beta RII promoter in tumor tissues, whereas most of the paracarcinoma tissues were free of methylation. The reduced TGF beta RII expression was highly significantly associated with the methylation event (P < 10(-4)). The reverse transcription-PCR analysis demonstrated a clear agreement between reduced TGF beta RII expression and decreased mRNA level of the gene in the tumor tissue samples. CONCLUSIONS: TGF beta RII plays an important role as a tumor suppressor in NSCLC carcinogenesis. The defective expression may serve as one of most important molecular mechanisms in explaining progression of the disease. In particular, aberrant 5' CpG methylation of the gene has explained the down-regulation of the gene at a transcriptional level.

Mutational analysis of the transforming growth factor beta receptor type I gene in primary non-small cell lung cancer.

Transforming growth factor-beta receptor-dependent signals are critical for cell growth and differentiation and are often disrupted during tumorigenesis. The entire coding region of TGFbetaRI and flanking intron sequences from 53 primary non-small cell lung cancer (NSCLC) tissues were examined for alterations using SSCP and direct sequencing. No somatic point mutations other than two silent mutations and a polymorphism were found in the TGFbetaRI gene. The two silent mutations located at codon 344 (AAT to AAC) and codon 406 (TTA to CTA), respectively, and the polymorphism was at the 24th base of intron 7 (G to A). To investigate whether the presence of this polymorphism is associated with NSCLC, we determined its allele distribution in all the 53 carcinomas and 89 normal controls. Interestingly, we found that the subjects with homozygous genotype A/A displayed more than 3-fold increased risk of developing NSCLC than the common wild genotype G/G. As the first report, the present study showed that TGFbetaRI gene is not a frequent site of spontaneous mutational inactivation while the detected polymorphism is frequent in the pathogenesis of NSCLC.