The role of two LEAFY paralogs from Idahoa scapigera (Brassicaceae) in the evolution of a derived plant architecture

Idahoa scapigera produces solitary flowers in the axils of rosette leaves without elongation of the shoot axis, a rosette-flowering architecture. Previous work with one of the two I. scapigera LFY paralogs, IscLFY1, showed that this gene caused aerial flowering rosettes in Arabidopsis thaliana. In this paper, we report that after three generations IscLFY1 transgenic lines are phenotypically indistinguishable from wild-type Arabidopsis, indicating that IscLFY1 protein is able to replace normal LFY function. Additionally, we found that ectopic LFY expression late in development can phenocopy aspects of the aerial rosette phenotype, suggesting that shoot compression caused by IscLFY1 could be caused by localized overexpression of a functional IscLFY protein. We also characterized the expression and function of the second I. scapigera LFY paralog, IscLFY2, in A. thaliana. In contrast to IscLFY1, this paralog was expressed in floral meristems and the shoot apical meristem (SAM). In I. scapigera, LFY-specific antibodies detected high protein levels in developing flowers but not in the apex, suggesting trans-regulatory differences between I. scapigera and A. thaliana. Most IscLFY2 transgenic A. thaliana plants were indistinguishable from wild type, but in a minority of lines the SAM was converted to a terminal flower as would be expected from the reporter-expression pattern. Taken together these results show that both I. scapigera paralogs have conserved LFY function, both proteins can rescue lfy and both can modify inflorescence architecture in an A. thaliana background: either by affecting internode elongation (IscLFY1) or by causing homeotic conversion of shoots into flowers (IscLFY2).     

长江宜宾江段铜鱼属鱼类种间食物关系

采用碳、氮稳定同位素技术对2012年4-5月长江宜宾江段铜鱼和圆口铜鱼的食物组成进行了分析,并利用多元统计分析方法探讨了铜鱼和圆口铜鱼种间食物关系,包括饵料相似性指数、重叠系数及2种鱼的摄食器官形态差异对食物组成的影响.结果表明:1)铜鱼的δ13C和δ15N变化范围分别为-21.15‰～-20.31‰和9.67‰～ 10.21‰,为偏动物性的杂食性鱼类;圆口铜鱼的δ13C和δ15N分别为-23.30‰～-21.18‰和7.40‰～ 9.21‰,相对铜鱼为偏植物性的杂食性鱼类,铜鱼和圆口铜鱼均与传统肠含物分析的结果存在一定的差异;2)两种鱼的食物相似性指数和食物重叠系数分别为78.7％和55.6％;3)主成分分析(PCA)表明,铜鱼和圆口铜鱼摄食器官形态特征存在一定的差异.长江宜宾江段铜鱼和圆口铜鱼种间竞争不激烈,作为向家坝蓄水前最后一次对长江宜宾江段铜鱼和圆口铜鱼食性及种间食物关系的调查,研究结果可为分析向家坝蓄水对宜宾江段鱼类营养结构的影响提供数据参考.     

Buckman's Paradox: variability and constraints on ammonoid ornament and shell shape

Buckman's Law of Covariation states that ammonoid shell shape and ornamentation are typically correlated, such that compressed, involute forms have light ornament while more inflated, evolute forms have heavier ornament. Such covariation has been observed in many ammonoid groups, and implies a link between the morphogenesis of shell shape and ornamentation. However, other evidence suggests that while ornament growth is controlled by the genetic‐developmental program of the ammonoid, shell shape is strongly influenced by environmental factors. These differing viewpoints lead to Buckman's Paradox – are ornamentation and shell shape tightly linked, as implied by Buckman's covariation, or is the morphogenesis of ornament controlled genetically, while shell shape is controlled environmentally? To address this issue, the variability of shell shape and rib morphology has been compared for a group of endemic acanthoceratid ammonites from the Cretaceous Western Interior Seaway of North America. If Buckman's Law holds due to a morphogenetic connection between shell shape and ornamentation, we would expect taxa with more variable shell shapes to also show more variable rib features and growth. Morphometric analysis of seven shell shape and two rib characters for the Western Interior acanthoceratids finds no such correlation, suggesting that shell shape and rib growth are controlled by different processes. Indeed, rib growth appears to be more constrained than shell shape, consistent with the view that ornamentation is more tightly controlled by the developmental‐genetic growth program of the ammonoid. These results emphasize the complexity of ammonoid morphogenesis and highlight our limited understanding of the causes underlying Buckman's Law.     

The giant panda ( Ailuropoda melanoleuca ) somatic nucleus can dedifferentiate in rabbit ooplasm and support early development of the reconstructed egg

The giant panda skeletal muscle cells, uterus epithelial cells and mammary gland cells from an adult individual were cultured and used as nucleus donor for the construction of intenpecies embryos by transferring them into enucleated rabbit eggs. All the three kinds of somatic cells were able to reprogram in rabbit ooplasm and support early embryo development, of which mammary gland cells were proven to be the best, followed by uterus epithelial cells and skeletal muscle cells. The experiments showed that direct injection of mammary gland cell into enucleated rabbit ooplasm, combined within vim development in ligated rabbit oviduct, achieved higher blastocyst development thanin vitro culture after the somatic cell was injected into the perivitelline space and fused with the enucleated egg by electrical stimulation. The chromosome analysis demonstrated that the genetic materials in reconstructed blastocyst cells were the same as that in panda somatic cells. In addition, giant panda mitochondrial DNA (mtDNA) was shown to exist in the intenpecies reconstructed blastocyst. The data suggest that (i) the ability of ooplasm to dedifferentiate somatic cells is not speciesspecific; (ii) there is compatibility between intenpecies somatic nucleus and ooplasm during early development of the reconstructed egg. Project supported by the 1998 Special Fund of the Chinese Academy of Sciences (KY95-J1-318) and a 1999 Special Fund from the Ministry of Science and Technology. Instruments were dominated by Mr. Shum Yam Wa, Heal Force Development Ltd.     

Widespread disruption of genomic imprinting in adult interspecies mouse (Mus) hybrids

Mammalian interspecies hybrids exhibit parent-of-origin effects in that offspring of reciprocal matings, even though genetically identical, frequently exhibit opposite phenotypes, especially in growth. This was also observed in hybridization with the genus Mus. These parent-of-origin effects suggested that imbalance in the expression of imprinted genes, which are expressed differentially, depending on their transmission through the maternal or paternal germline, and/or differential loss-of-imprinting (LOI) could underlie these opposite growth phenotypes in reciprocal mammalian hybrids. Here we report that tissue-specific LOI occurs in adult Mus hybrids. Contrary to expectations, LOI patterns were not consistent with a direct influence of altered expression levels of imprinted genes on growth. Bisulfite sequencing revealed that reactivation of maternal alleles of Peg3 and Snrpn in specific tissues was accompanied by partial demethylation at their potential imprinting control regions. We propose that abnormal reprogramming after fertilization and during preimplantation development is in part responsible for hybrid dysgenesis, for which a strong epigenetic basis has been demonstrated.     

Role of formate and hydrogen in the degradation of propionate and butyrate by defined suspended cocultures of acetogenic and methanogenic bacteria

The butyrate-degradingSyntrophospora bryantii degrades butyrate and a propionate-degrading strain (MPOB) degrades propionate in coculture with the hydrogen- and formate-utilizingMethanospirillum hungatii orMethanobacterium formicicum. However, the substrates are not degraded in constructed cocultures with twoMethanobrevibacter arboriphilus strains which are only able to consume hydrogen. Pure cultures of the acetogenic bacteria form both hydrogen and formate during butyrate oxidation with pentenoate as electron acceptor and during propionate oxidation with fumarate as electron acceptor. Using the highest hydrogen and formate levels which can be reached by the acetogens and the lowest hydrogen and formate levels which can be maintained by the methanogens it appeared that the calculated formate diffusion rates are about 100 times higher than the calculated hydrogen diffusion rates.     

Alanine as an end product during fermentation of monosaccharides byClostridium strain P2

The thermophilicClostridium P2 was isolated from a semi-continuously fed reactor with high ammonium concentration. This bacterium formed substantial amounts of L-alanine as a major fermentation product from glucose, fructose and mannose. Low amounts of acetate, butyrate, carbon dioxide and hydrogen were also formed. A high partial pressure of hydrogen inhibited the degradation of the monosaccharides, whereas hydrogen removal, in the form of methanogenesis was found to be stimulatory. However, the amount of alanine produced per mole of hexose degraded did not change. Hexose degradation and alanine production were favoured by high ammonium concentrations. Nuclear magnetic resonance spectroscopy studies provided strong evidence that an active Embden-Meyerhof-Parnas pathway existed and that alanine was produced via an amination of pyruvate.     

云贵鹅耳枥群落演替中乔木树种间协变的研究

采用Ｓｐｅａｒｍａｎ秩相关系数探讨了贵阳喀斯特山地云贵鹅耳枥群落演替中１６种常见乔木树种间的协变,并对这些乔木树种间的协变关系及其对群落的性质、结构和动态的影响进行了分析。     

Allometric relations of teeth and jaws in man

Static adult intraspecific allometry of jaws and teeth was investigated in a sample of 100 Negro crania. The relations between tooth area, postcanine surface, incisor surface, and four viscerocranial measures were examined separately for males and females. Our results indicate a marked lack of morphological integration between P-sets within the orofacial subregion and a similar lack of correspondence between jaw size and tooth size. Allometric analyses indicate that mandibular length scales negatively allometric to maxilloalveolar length and to bigonial width, that canine base area scales positively to upper and lower jaw length, and that all the other teeth scale negatively to jaw length. The postcanine surface area was found to be negatively allometric to the canine base area, which in turn scaled isometrically to incisor surface. Hence, any lengthening of the mandible will tend to be associated with a relative shortening of the maxilla, with relatively larger canines and a relative reduction of the cheek teeth.     

Fermentation of isoleucine and arginine by pure and syntrophic cultures of Clostridium sporogenes

Abstract The fermentation of isoleucine, arginine and isoleucine + arginine by pure and syntrophic cultures of Clostridium sporogenes was investigated. Growth of C. sporogenes on isoleucine, if any, was poor, but some isoleucine was fermented to 2-methylbutyrate and hydrogen. In syntrophic cultures with Methanobacterium formicicum or Methanosarcina barkeri growth was better, and isoleucine was completely fermented, the hydrogen being used for methane production. Pure cultures of C. sporogenes grew on arginine and produced 5-aminovalerate, ornithine and acetate. The reducing equivalents for 5-aminovalerate production from intermediarily formed proline were provided by oxidative conversion of arginine to acetate and by oxidative metabolism of some amino acids present in the yeast extract. However, when isoleucine was available together with arginine in syntrophic cultures of C. sporogenes and M. formicicum , the reducing equivalents for arginine fermentation came mainly from the oxidation of isoleucine (Stickland reaction), and the hydrogen produced in excess served for the reduction of CO₂ to methane.