The variety of thermal conduction resulting from segmented degree of heat source body and its bearing on temperature change

The differences of thermal conduction and its temperature-varying track of the heat source body at various structural environments have been studied. Hypothetically , geologic heat source body is cut successively into several segregative bodies with a fixed cubage . With the segmented number increasing , the conductive surface area of heat source body begins to get larger, which separately is similar to the heat geologic body in different tectonic zones that has a various enclosed coefficient . Finite-element simulation result shows that the thermal conduction speed of spreading from the heat source body to its wall rock is slow→higher→ highest, when heat source bodies are situated respectively at compressive, shear and tensile deformation zones, corresponding rates of their temperature drop are low→ higher→ highest . Research indicates that the temperature ' s dropping rate of heat source body has an inverse relationship with enclosed coefficient η for different structural zones . This result can explain the tectono-physicochemical reason of magmatite evolution and its. difference .     

Mitochondrial glutamate acts as a messenger in glucose-induced insulin exocytosis

The hormone insulin is stored in secretory granules and released from the pancreatic beta-cells by exocytosis. In the consensus model of glucose-stimulated insulin secretion, ATP is generated by mitochondrial metabolism, promoting closure of ATP-sensitive potassium (KATP) channels, which depolarizes the plasma membrane. Subsequently, opening of voltage-sensitive Ca2+ channels increases the cytosolic Ca2+ concentration ([Ca2+]c) which constitutes the main trigger initiating insulin exocytosis. Nevertheless, the Ca2+ signal alone is not sufficient for sustained secretion. Furthermore, glucose elicits a secretory response under conditions of clamped, elevated [Ca2+]c. A mitochondrial messenger must therefore exist which is distinct from ATP. We have now identified this as glutamate. We show that glucose generates glutamate from beta-cell mitochondria. A membrane-permeant glutamate analogue sensitizes the glucose-evoked secretory response, acting downstream of mitochondrial metabolism. In permeabilized cells, under conditions of fixed [Ca2+]c, added glutamate directly stimulates insulin exocytosis, independently of mitochondrial function. Glutamate uptake by the secretory granules is likely to be involved, as inhibitors of vesicular glutamate transport suppress the glutamate-evoked exocytosis. These results demonstrate that glutamate acts as an intracellular messenger that couples glucose metabolism to insulin secretion.     

Sequence and analysis of chromosome 2 of the plant Arabidopsis thaliana

Arabidopsis thaliana (Arabidopsis) is unique among plant model organisms in having a small genome (130-140 Mb), excellent physical and genetic maps, and little repetitive DNA. Here we report the sequence of chromosome 2 from the Columbia ecotype in two gap-free assemblies (contigs) of 3.6 and 16 megabases (Mb). The latter represents the longest published stretch of uninterrupted DNA sequence assembled from any organism to date. Chromosome 2 represents 15% of the genome and encodes 4,037 genes, 49% of which have no predicted function. Roughly 250 tandem gene duplications were found in addition to large-scale duplications of about 0.5 and 4.5 Mb between chromosomes 2 and 1 and between chromosomes 2 and 4, respectively. Sequencing of nearly 2 Mb within the genetically defined centromere revealed a low density of recognizable genes, and a high density and diverse range of vestigial and presumably inactive mobile elements. More unexpected is what appears to be a recent insertion of a continuous stretch of 75% of the mitochondrial genome into chromosome 2.     

A structural change in the kinesin motor protein that drives motility

Kinesin motors power many motile processes by converting ATP energy into unidirectional motion along microtubules. The force-generating and enzymatic properties of conventional kinesin have been extensively studied; however, the structural basis of movement is unknown. Here we have detected and visualized a large conformational change of an approximately 15-amino-acid region (the neck linker) in kinesin using electron paramagnetic resonance, fluorescence resonance energy transfer, pre-steady state kinetics and cryo-electron microscopy. This region becomes immobilized and extended towards the microtubule 'plus' end when kinesin binds microtubules and ATP, and reverts to a more mobile conformation when gamma-phosphate is released after nucleotide hydrolysis. This conformational change explains both the direction of kinesin motion and processive movement by the kinesin dimer.     

Oldest playable musical instruments found at Jiahu early Neolithic site in China

Excavations at the early Neolithic site of Jiahu in Henan Province, China have produced what may be the earliest complete, playable, tightly-dated multinote musical instruments. Jiahu was occupied from 7000 BC to 5700 BC, considerably antedating the well known Peiligang culture. Here we describe six exquisitely made complete flutes which were found in radiocarbon-dated excavation layers, along with fragments of perhaps 30 more. The flutes are made from the ulnae of the red-crowned crane (Grus japonensis Millen) and have 5, 6, 7 and 8 holes. The best preserved flute has been played and tonally analysed. In addition to early musical artefacts, the archaeological record at Jiahu contains important information on the very foundations of Chinese society. We describe the archaeological characteristics of the Jiahu site, details concerning its dating, its place in the prehistory of the Chinese Neolithic, the ethnicity of its population and the results of a tonal analysis of a nearly 9,000-year-old musical instrument found there.     

Functional recognition of the 3' splice site AG by the splicing factor U2AF35

In metazoans, spliceosome assembly is initiated through recognition of the 5' splice site by U1 snRNP and the polypyrimidine tract by the U2 small nuclear ribonucleoprotein particle (snRNP) auxiliary factor, U2AF. U2AF is a heterodimer comprising a large subunit, U2AF65, and a small subunit, U2AF35. U2AF65 directly contacts the polypyrimidine tract and is required for splicing in vitro. In comparison, the role of U2AF35 has been puzzling: U2AF35 is highly conserved and is required for viability, but can be dispensed with for splicing in vitro. Here we use site-specific crosslinking to show that very early during spliceosome assembly U2AF35 directly contacts the 3' splice site. Mutational analysis and in vitro genetic selection indicate that U2AF35 has a sequence-specific RNA-binding activity that recognizes the 3'-splice-site consensus, AG/G. We show that for introns with weak polypyrimidine tracts, the U2AF35-3'-splice-site interaction is critical for U2AF binding and splicing. Our results demonstrate a new biochemical activity of U2AF35, identify the factor that initially recognizes the 3' splice site, and explain why the AG dinucleotide is required for the first step of splicing for some but not all introns.