Iron-sulfur Cluster Biosynthesis in Methanogens

Methanogens live in a syntrophic consortium with bacteria, taking advantage of the metabolic abilities of their syntrophic partners to overcome energetic barriers and break down compounds that they cannot digest by themselves. Interspecies electron transfer, which is a major type of microbial communication in syntrophic processes, improves methanogenesis and anaerobic oxidization of methane (AOM) processes involved in syntrophic consortia. These processes have a significant impact on the global carbon cycle. Most of the essential enzymes involved in methanogenesis are iron-sulfur proteins. Iron-sulfur clusters are one of the oldest and most versatile cofactors present in all domains of life. To date, four different Fe-S cluster assembly systems have been identified in bacteria (ISC, NIF, and SUF) and eukaryotes (ISC, CIA, and SUF). However, little is known about the Fe-S cluster assembly system in archaea. Only three proteins related to Fe-S cluster assembly are conserved in almost all sequenced archaea: SufB, SufC, and the ApbC/Nbp35 homolog. The ancestral suf operon likely only contains sufBC. Here, we provide the biochemical and spectroscopic characterizations of the Methanococcus maripaludis (Mmp) SufB, SufC, and ApbC proteins. Our major findings include: (i) The SufB and SufC form a SufB2C2 complex in methanogens; (ii) The SufB2C2 is a functional scaffold, which can assemble and transfer a [4Fe-4S] cluster; (iii) The [4Fe-4S] cluster of the SufB2C2 complex is located on three highly conserved cysteine residues, Cys218, Cys237, and Cys240, on SufC; (iv) The SufC has ATPase activity, which is not required for Fe-S cluster assembly and transfer activities; (v) The archaeal Nbp35/ApbC homolog contains a [4Fe-4S] cluster which can be transferred to activate aconitase; (vi) M. maripaludis shows no growth defect when the archaeal Nbp35/ApbC gene is deleted. Together, our results suggest that the SufB2C2 complex is a functional essential scaffold for Fe-S cluster biosynthesis in archaea and that the archaeal Nbp35/ApbC homolog is a functional, but not essential scaffold/carrier protein for Fe-S cluster maturation in M. maripaludis

An Embryonic Myosin Isoform Enables Stretch Activation and Cyclical Power in Drosophila Jump Muscle

AbstractThe mechanism behind stretch activation (SA), a mechanical property that increases muscle force and oscillatory power generation, is not known. We used Drosophila transgenic techniques and our new muscle preparation, the jump muscle, to determine if myosin heavy chain isoforms influence the magnitude and rate of SA force generation. We found that Drosophila jump muscles show very low SA force and cannot produce positive power under oscillatory conditions at pCa 5.0. However, we transformed the jump muscle to be moderately stretch-activatable by replacing its myosin isoform with an embryonic isoform (EMB). Expressing EMB, jump muscle SA force increased by 163% and it generated net positive power. The rate of SA force development decreased by 58% with EMB expression. Power generation is Pi dependent as >4 mM Pi was required for positive power from EMB. Pi increased EMB SA force, but not wild-type SA force. Our data suggest that when muscle expressing EMB is stretched, EMB is more easily driven backward to a weakly bound state than wild-type jump muscle. This increases the number of myosin heads available to rapidly bind to actin and contribute to SA force generation. We conclude that myosin heavy chain isoforms influence both SA kinetics and SA force, which can determine if a muscle is capable of generating oscillatory power at a fixed calcium concentration

The Study on Prospect and Early Opportunities for Carbon Capture and Storage in Guangdong Province, China

AbstractCCS is regarded as an important and strategic technology option to reduce CO2 emission, and has received tremendous attention around the world. Guangdong, as the largest economic and energy-consuming province in China, is necessary to take CCS as an important option to reduce its future CO2 emission. This paper presents the partial outcome of the first CCS-related research in Guangdong, which is aiming for preliminary assessment on the feasibility of CCS development in Guangdong. The main objective of the study is to characterize the industrial CO2 emissions and understand its CCS prospects. Coal-fired power plants in Guangdong are the major point sources, contributing to more than 90% of CO2 emissions from the electric power generation. The power plants are mainly located in the Pearl River Delta, while the newly built and projected large plants are mainly located in eastern coastal zone, which provides a great potential for CO2 capture. For the storage potential, there are six sedimentary basins in or around Guangdong with effective storage capacity of 568 GtCO2. Since the onshore storage capacity in Guangdong is limited, the northern portion of the Pear River Mouth Basin (PRMB) was considered the most promising choice for Guangdong to storage CO2. By considering the distance between source and sink, technology maturity, land resources and other factors, it can be concluded that in the short term the power plants under construction and projected located in the eastern coastal areas will be the most promising resources for CO2 capture and the corresponding storage sites are the existing oil/gas fields which located in the northeast of PRMB. But in the long term, as technologies and the international carbon market mature, the extensively retrofitting of existing coal-fired power plants in the Pearl River Delta region with CO2 capture will become possible. In order to promote the development of CCS in Guangdong, more basic investigation and policy research are necessary in the coming years

Diaqua­(2,9-dimethyl-1,10-phenanthroline-κ2 N,N′)(4-hydroxy­benzoato-κ2 O,O′)cobalt(II) nitrate dihydrate

In the title compound, [Co(C7H5O3)(C14H12N2)(H2O)2]NO3·2H2O, the CoII ion is six-coordinated by two N atoms of a 2,9-dimethyl-1,10-phenanthroline (dmphen) ligand, two carboxyl­ate O atoms of one 4-hydroxy­benzoate anion and two O atoms of two water mol­ecules, in a distorted octa­hedral environment; the two water mol­ecules occupy the apical positions. In the crystal structure, the ionic units and water mol­ecules are linked through O—H⋯O hydrogen bonds, leading to the formation of a three-dimensional network. In addition, π–π inter­actions between a pyridine ring of the dmphen ligand and the benzene ring of the hydroxy­benzoate anion [centroid–centroid separation = 3.6861 (3) Å] are observed

Transformer Compression via Subspace Projection

We propose TCSP, a novel method for compressing a transformer model by focusing on reducing the hidden size of the model. By projecting the whole transform model into a subspace, we enable matrix operations between the weight matrices in the model and features in a reduced-dimensional space, leading to significant reductions in model parameters and computing resources. To establish this subspace, we decompose the feature matrix, derived from different layers of sampled data instances, into a projection matrix. For evaluation, TCSP is applied to compress T5 and BERT models on the GLUE and SQuAD benchmarks. Experimental results demonstrate that TCSP achieves a compression ratio of 44\% with at most 1.6\% degradation in accuracy, surpassing or matching prior compression methods. Furthermore, TCSP exhibits compatibility with other methods targeting filter and attention head size compression.Comment: 21 pages, 1 figure

Spatial Influence Analysis of Traffic Safety in Diverging Areas between Freeway Segments and Off Ramps

There tend to be more crashes occurring in freeway diverging segments due to increasing traffic conflicts between diverging vehicles and nondiverging vehicles. The diverging segments have a safety impact on the precedent basic segments and the following off ramps. It is always a challenge to accurately define the safety influential area of freeway diverging segments. In previous studies, fixed buffer in size is pregiven for crash frequency analysis in diverging segments, which lacks theoretical and practical support. In this study, the safety influential area was investigated from the statistical point of view. Data from a geocoded GIS crash database for Colorado Springs metropolitan area was used; the statistically significant factors associated with crash frequency were examined for the spatial influence of freeway diverging segments. Also, the generalized linear models with negative binomial link function were applied to predict the crash frequency for freeway diverging segments and off ramps based on the influential area. The results may give some insights into the causation of crashes on diverging segments and off-ramp intersections

Apoptosis of supraoptic AVP neurons is involved in the development of central diabetes insipidus after hypophysectomy in rats

<p>Abstract</p> <p>Background</p> <p>It has been reported that various types of axonal injury of hypothalamo-neurohypophyseal tract can result in degeneration of the magnocellular neurons (MCNs) in hypothalamus and development of central diabetes insipidus (CDI). However, the mechanism of the degeneration and death of MCNs after hypophysectomy in vivo is still unclear. This present study was aimed to disclose it and to figure out the dynamic change of central diabetes insipidus after hypophysectomy.</p> <p>Results</p> <p>The analysis on the dynamic change of daily water consumption (DWC), daily urine volume(DUV), specific gravity of urine(USG) and plasma vasopressin concentration showed that the change pattern of them was triphasic and neuron counting showed that the degeneration of vasopressin neurons began at 10 d, aggravated at 20 d and then stabilized at 30 d after hypophysectomy. There was marked upregulation of cleaved Caspase-3 expression of vasopressin neurons in hypophysectomy rats. A "ladder" pattern of migration of DNA internucleosomal fragments was detected and apoptotic ultrastructure was found in these neurons. There was time correlation among the occurrence of diabetes insipidus, the changes of plasma vasopressin concentration and the degeneration of vasopressin neurons after hypophysectomy.</p> <p>Conclusion</p> <p>This study firstly demonstrated that apoptosis was involved in degeneration of supraoptic vasopressin neurons after hypophysectomy in vivo and development of CDI. Our study on time course and correlations among water metabolism, degeneration and apoptosis of vasopressin neurons suggested that there should be an efficient therapeutic window in which irreversible CDI might be prevented by anti-apoptosis.</p