Homologues of Twisted gastrulation are extracellular cofactors in antagonism of BMP signalling

Twisted gastrulation (TSG) is involved in specifying the dorsal-most cell fate in Drosophila embryos, but its mechanism of action is poorly understood. TSG has been proposed to modify the action of Short gastrulation (SOG), thereby increasing signalling by the bone morphogenetic protein (BMP) Decapentaplegic. SOG, an inhibitor of BMP signalling, is in turn inactivated by the protease Tolloid. Here we identify Tsg gene products from human, mouse, Xenopus, zebrafish and chick. Expression patterns in mouse and Xenopus embryos are consistent with in vivo interactions between Tsg, BMPs and the vertebrate SOG orthologue, chordin. We show that Tsg binds both the vertebrate Decapentaplegic orthologue BMP4 and chordin, and that these interactions have multiple effects. Tsg increases chordin's binding of BMP4, potentiates chordin's ability to induce secondary axes in Xenopus embryos, and enhances chordin cleavage by vertebrate tolloid-related proteases at a site poorly used in Tsg's absence; also, the presence of Tsg enhances the secondary axis-inducing activity of two products of chordin cleavage. We conclude that Tsg acts as a cofactor in chordin's antagonism of BMP signalling.     

Genetic similarity between mates and extra-pair parentage in three species of shorebirds

Matings between close relatives often reduce the fitness of offspring, probably because homozygosity leads to the expression of recessive deleterious alleles. Studies of several animals have shown that reproductive success is lower when genetic similarity between parents is high, and that survival and other measures of fitness increase with individual levels of genetic diversity. These studies indicate that natural selection may favour the avoidance of matings with genetically similar individuals. But constraints on social mate choice, such as a lack of alternatives, can lead to pairing with genetically similar mates. In such cases, it has been suggested that females may seek extra-pair copulations with less related males, but the evidence is weak or lacking. Here we report a strong positive relationship between the genetic similarity of social pair members and the occurrence of extra-pair paternity and maternity ('quasi-parasitism') in three species of shorebirds. We propose that extra-pair parentage may represent adaptive behavioural strategies to avoid the negative effects of pairing with a genetically similar mate.     

Dominant isolated renal magnesium loss is caused by misrouting of the Na(+),K(+)-ATPase gamma-subunit

Primary hypomagnesaemia is composed of a heterogeneous group of disorders characterized by renal or intestinal Mg(2+) wasting, often associated with disturbances in Ca(2+) excretion. We identified a putative dominant-negative mutation in the gene encoding the Na(+), K(+)-ATPase gamma-subunit (FXYD2), leading to defective routing of the protein in a family with dominant renal hypomagnesaemia.     

野西瓜多糖分离纯化及其质量浓度研究

研究了野西瓜多糖分离纯化、质量浓度及分子质量.通过木瓜蛋白酶-Sevag法脱除蛋白,采用双氧水及透析法除去色素及小分子,利用分步醇沉法得到质量最大的CSPSⅠ,并对其进行DEAE-52柱层析,进而得到糖质量浓度最高的组分CSPSⅠC.纯度鉴定确认CSPSⅠC为高纯度多糖.对CSPSⅠC糖质量浓度、糖醛酸、硫酸基质量浓度进行测定并考察了其方法学,证实得到的结果准确可靠.采用高效液相色谱得到了CSPSⅠC的相对分子质量.通过对野西瓜多糖分离纯化及质量浓度测定为继续深入研究野西瓜多糖奠定了基础.     

石蒜科植物朱顶红药用价值研究

朱顶红Hippeastrum vittatum (Ait.) Herb是一种石蒜科的草本植物.目前可见的朱顶红大多是人工培育品种.朱顶红作为一种传统中药,有良好清热解毒的功效,民间常用于治痈疮肿毒.另外,朱顶红的用药部位一般为鳞茎,其性温,味辛,并有一定的毒性.随中药现代化的发展,中药朱顶红中化学成分得以分离.研究发现朱顶红中提取分离的化学可体现出不同的药理作用.对朱顶红的化学成分及药理作用进行整理综述.以期为后续朱顶红的研究提供理论依据.     

上天入地——港珠澳大桥

正2018年10月23日,连接香港、珠海和澳门三地的港珠澳大桥通车。这座大桥被誉为工程史上的奇迹,更是中国跨海大桥中的纪念碑。它全长55千米,横跨风高浪急的广东伶仃洋,需要在120年的使用寿命里抵抗台风和地震的侵袭,建造困难前无古人。大桥还有一节深埋在海底的隧道,由两座新建的人工小岛与大桥连接。整座大桥充满科技亮点和令人赞叹的智慧结晶,在便利交通的同时,也让中国桥梁又一次震惊世界。     

单燃料天然气发动机控制系统设计与试验研究

以单缸汽油机为对象,研制了天然气发动机单燃料电控喷射系统,进行了发动机供气系统设计、点火系统改进、空燃比优化、电控系统研制及发动机控制参数匹配试验等研究工作,试验结果表明,采用天然气电控缸内直喷技术可有效提高发动机的充气效率,使天然气发动机的功率基本恢复到原汽油机的水平。     

放飞爱情鸟

也不知道是什么时候,一只鸟飞到了我家的阳台上,丈夫将它捉住,关进了鸟笼里。于是,这只鸟只好孤独地在笼子中歌唱着,终于有一天,它的歌声引来了另一只鸟,从此,阳台上鸟语花香。 我能看出笼子里的鸟想飞出去,它在笼子里不停地扑腾着,尽力响应着它的伙伴在笼子外的呼唤;笼外的鸟悄悄地飞近,最先是停在我家的茉莉花花枝上,后来,飞到我晾衣服的杆子上,终于,它飞到鸟笼上,和笼子里的鸟面对面地叫了起来,旁若无人,无拘无束,那份亲密确实令人羡慕。当笼外的鸟飞走,去找食的时候,笼子里的鸟并没有平息下来,它叫得更欢,好像…     

Mutations in the gene encoding the synaptic scaffolding protein SHANK3 are associated with autism spectrum disorders

SHANK3 (also known as ProSAP2) regulates the structural organization of dendritic spines and is a binding partner of neuroligins; genes encoding neuroligins are mutated in autism and Asperger syndrome. Here, we report that a mutation of a single copy of SHANK3 on chromosome 22q13 can result in language and/or social communication disorders. These mutations concern only a small number of individuals, but they shed light on one gene dosage-sensitive synaptic pathway that is involved in autism spectrum disorders.     

Long-term sensitivity of soil carbon turnover to warming

The sensitivity of soil carbon to warming is a major uncertainty in projections of carbon dioxide concentration and climate. Experimental studies overwhelmingly indicate increased soil organic carbon (SOC) decomposition at higher temperatures, resulting in increased carbon dioxide emissions from soils. However, recent findings have been cited as evidence against increased soil carbon emissions in a warmer world. In soil warming experiments, the initially increased carbon dioxide efflux returns to pre-warming rates within one to three years, and apparent carbon pool turnover times are insensitive to temperature. It has already been suggested that the apparent lack of temperature dependence could be an artefact due to neglecting the extreme heterogeneity of soil carbon, but no explicit model has yet been presented that can reconcile all the above findings. Here we present a simple three-pool model that partitions SOC into components with different intrinsic turnover rates. Using this model, we show that the results of all the soil-warming experiments are compatible with long-term temperature sensitivity of SOC turnover: they can be explained by rapid depletion of labile SOC combined with the negligible response of non-labile SOC on experimental timescales. Furthermore, we present evidence that non-labile SOC is more sensitive to temperature than labile SOC, implying that the long-term positive feedback of soil decomposition in a warming world may be even stronger than predicted by global models.