澳大利亚及斯洛文尼亚稻绿蝽(Nezara viridula)外生殖器微细结构电镜观察

澳大利亚和斯洛文尼亚的稻绿蝽因不完全的生殖隔离而曾被认为是两个不同的但互为姊妹的种群 .作者对采自于澳大利亚和斯洛文尼亚的稻绿蝽的雄性、雌性外生殖器及触角节上的感觉毛进行了解剖比较和扫描电子显微镜下的观察研究 ,旨在从外生殖器及触角感觉器等方面找出支持该观点的证据 .研究证明 ,上述几种器官的微细结构在两个种群间并无显著的差异 ,不存在将二者分为姊妹种的依据 .故两个群体间生殖隔离现象与外生殖器的结构无关 .     

Supraphysiological dosages of vitamins and their implications in man

Some recent evidence on the benefits and hazards of elevated dosages of vitamins is summarized. Special emphasis is given on the safety of vitamins A, D, K1 and B6. Furthermore, the possibly beneficial effects of vitamins for athletic performance as well as the preventive potential of antioxidative vitamins and of carotenoids against cancer are discussed.     

Morphological and ecological complexity in early eukaryotic ecosystems.

Molecular phylogeny and biogeochemistry indicate that eukaryotes differentiated early in Earth history. Sequence comparisons of small-subunit ribosomal RNA genes suggest a deep evolutionary divergence of Eukarya and Archaea; C27-C29 steranes (derived from sterols synthesized by eukaryotes) and strong depletion of 13C (a biogeochemical signature of methanogenic Archaea) in 2,700 Myr old kerogens independently place a minimum age on this split. Steranes, large spheroidal microfossils, and rare macrofossils of possible eukaryotic origin occur in Palaeoproterozoic rocks. Until now, however, evidence for morphological and taxonomic diversification within the domain has generally been restricted to very late Mesoproterozoic and Neoproterozoic successions. Here we show that the cytoskeletal and ecological prerequisites for eukaryotic diversification were already established in eukaryotic microorganisms fossilized nearly 1,500 Myr ago in shales of the early Mesoproterozoic Roper Group in northern Australia.     

Mutations in the desmosomal protein plakophilin-2 are common in arrhythmogenic right ventricular cardiomyopathy

Arrhythmogenic right ventricular cardiomyopathy (ARVC) is associated with fibrofatty replacement of cardiac myocytes, ventricular tachyarrhythmias and sudden cardiac death. In 32 of 120 unrelated individuals with ARVC, we identified heterozygous mutations in PKP2, which encodes plakophilin-2, an essential armadillo-repeat protein of the cardiac desmosome. In two kindreds with ARVC, disease was incompletely penetrant in most carriers of PKP2 mutations.     

Compact sources as the origin of the soft gamma-ray emission of the Milky Way

The Milky Way is known to be an abundant source of gamma-ray photons, now determined to be mainly diffuse in nature and resulting from interstellar processes. In the soft gamma-ray domain, point sources are expected to dominate, but the lack of sensitive high-resolution observations did not allow for a clear estimate of the contribution from such sources. Even the best imaging experiment revealed only a few point sources, accounting for about 50% of the total Galactic flux. Theoretical studies were unable to explain the remaining intense diffuse emission. Investigating the origin of the soft gamma-rays is therefore necessary to determine the dominant particle acceleration processes and to gain insights into the physical and chemical equilibrium of the interstellar medium. Here we report observations in the soft gamma-ray domain that reveal numerous compact sources. We show that these sources account for the entirety of the Milky Way's emission in soft gamma-rays, leaving at most a minor role for diffuse processes.     

Molecular gas in the host galaxy of a quasar at redshift z = 6.42

Observations of molecular hydrogen in quasar host galaxies at high redshifts provide fundamental constraints on galaxy evolution, because it is out of this molecular gas that stars form. Molecular hydrogen is traced by emission from the carbon monoxide molecule, CO; cold H2 itself is generally not observable. Carbon monoxide has been detected in about ten quasar host galaxies with redshifts z > 2; the record-holder is at z = 4.69 (refs 1-3). Here we report CO emission from the quasar SDSS J114816.64 + 525150.3 (refs 5, 6) at z = 6.42. At that redshift, the Universe was only 1/16 of its present age, and the era of cosmic reionization was just ending. The presence of about 2 x 1010 M\circ of H2 in an object at this time demonstrates that molecular gas enriched with heavy elements can be generated rapidly in the youngest galaxies.