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Sex determination mechanisms evolve surprisingly rapidly, yet little is known in the large nematode phylum other than for Caenorhabditis elegans, which relies on chromosomal XX-XO sex determination and a dosage compensation mechanism. Here we analyze by sex-specific genome sequencing and genetic analysis sex determination in two fungal feeding/plant-parasitic Bursaphelenchus nematodes and find that their sex differentiation is more likely triggered by random, epigenetic regulation than by more well-known mechanisms of chromosomal or environmental sex determination. There is no detectable difference in male and female chromosomes, nor any linkage to sexual phenotype. Moreover, the protein sets of these nematodes lack genes involved in X chromosome dosage counting or compensation. By contrast, our genetic screen for sex differentiation mutants identifies a Bursaphelenchus ortholog of tra-1, the major output of the C. elegans sex determination cascade. Nematode sex determination pathways might have evolved by “bottom-up” accretion from the most downstream regulator, tra-1.

Cu(In,Ga)Se2 (CIGS) solar cells were fabricated by thermal diffusion of Zn into p ‐type CIGS films using dimethylzinc [(CH3)2Zn: DMZn] vapor, in order to form CIGS pn ‐homojunction. This method requires no additional processing equipment, because diffusion can be carried out subsequent to the CIGS growth. The average conversion efficiency of the CIGS solar cells consisting of n ‐type MgZnO transparent conducting oxide (TCO) film and n ‐CIGS:Zn/p ‐CIGS structure (4%) was improved by a factor of two in comparison with the case for undoped CIGS absorbing layer (2%). The appropriate flow time of DMZn was 3 s, from which the diffusion depth is estimated as about 150 nm. The method is highly advantageous for development of low‐cost solar modules. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

Selenization growth of purely single‐phase, polycrystalline CuIn1–x Alx Se2 (0 ≤ x ≤ 0.26) alloy films was demonstrated using a less‐hazardous metal‐organic selenide, diethylselenide [(C2H5)2Se: DESe]. Without additional thermal annealing, approximately 2.0‐μm‐thick alloy films exhibiting X‐ray diffraction peaks originating exclusively from the chalcopyrite structure were obtained. Their low temperature photoluminescence spectra were dominated by characteristic donor‐acceptor pair emissions usually seen in the state‐of‐the‐art CuInAlSe2 photoabsorbing layers. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

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