A morphometric investigation of the small yellow croaker (Larimichthys polyactis Bleeker, 1877): evidence for subpopulations on the Chinese coast

In this study the morphometric characteristics based on the truss network system were constructed from the body shapes and used to investigate the population structure of the small yellow croaker (Larimichthys polyactis Bleeker, 1877). From April to June 2013, a total of 431 fish samples were collected from commercial catches acquired with bottom trawlers (20 × 20 mm) in seven main spawning grounds along the coast of China. The results of principal component and discriminant function analyses indicated a clear distinction among the regional stocks and within the Haizhou Bay (HZB) stock. Observed differences primarily involved head measurements, body length and tail size, which were associated with environmental factors. Latitudinal gradient of the stock distribution and the relationship among the stocks provided further evidence for the existence of subpopulations and the re‐division of the East China Sea group. Moreover, the temporal inter‐structure of the HZB stock is a potential reason for the contrast in results from previous studies. Additional thorough studies of migration trajectories are required for a conclusive and improved understanding of the population structure.     

Toxicological and biochemical characterizations of GSTs in Liposcelis bostrychophila Badonnel (Psocop., Liposcelididae)

Abstract: The toxicological and biochemical characteristics of glutathione S‐transferases (GSTs) in the resistant and susceptible strains of Liposcelis bostrychophila were investigated. The two resistant strains were the dichlorvos‐resistant strain (DDVP‐R) and PH₃‐resistant strain (PH₃‐R), and the resistance factors were 22.36 and 4.51, respectively. Compared with their susceptible counterparts, the activities per insect and specific activities of GSTs in DDVP‐R and PH₃‐R were significantly higher. The apparent Michaelis–Menten constant values (K_m) for 1‐chloro‐2,4‐dinitrobenzene (CDNB) were obviously lower in DDVP‐R and PH₃‐R (i.e. lower K_m values, 1.5625 mm for DDVP‐R and 0.6230 mm for PH₃‐R) when compared with their susceptible counterpart (K_m = 3.5520), indicating a higher affinity to the substrate CDNB in resistant strains. In contrast, the catalytic activity of GSTs towards CDNB in the susceptible strain was significantly higher than those in resistant strains. It was noticeable that when reduced glutathione (GSH) was used as substrate, GSTs from resistant strains both indicated a significantly declined affinity. For the catalytic activity of GSTs towards GSH, only the V_max value in DDVP‐R increased significantly compared with that from the susceptible strain, suggesting an overexpression of GST in this resistant strain. The inhibition kinetics of insecticides to GSTs in vitro revealed that dichlorvos and paraoxon possessed excellent inhibition effects on GSTs. The susceptible strain showed higher sensitivity (I₅₀ = 0.9004 mm ) to dichlorvos than DDVP‐R and PH₃‐R (higher I₅₀s, 8.0955 mm for DDVP‐R and 9.3346 mm for PH₃‐R). As for paraoxon, there was a similar situation. The resistant strains both suggested a higher I₅₀ (1.8735 mm for DDVP‐R, and 0.4291 mm for PH₃‐R) compared with the susceptible strain (0.2943 mm ). These suggested that an elevated detoxification ability of GSTs developed in the resistant strains.     

The arginine finger of the Bloom syndrome protein: its structural organization and its role in energy coupling

RecQ family helicases are essential in maintaining chromosomal DNA stability and integrity. Despite extensive studies, the mechanisms of these enzymes are still poorly understood. Crystal structures of many helicases reveal a highly conserved arginine residue located near the γ-phosphate of ATP. This residue is widely recognized as an arginine finger, and may sense ATP binding and hydrolysis, and transmit conformational changes. We investigated the existence and role of the arginine finger in the Bloom syndrome protein (BLM), a RecQ family helicase, in ATP hydrolysis and energy coupling. Our studies by combination of structural modelling, site-directed mutagenesis and biochemical and biophysical approaches, demonstrate that mutations of residues interacting with the γ-phosphate of ATP or surrounding the ATP-binding sites result in severe impairment in the ATPase activity of BLM. These mutations also impair BLM's DNA-unwinding activities, but do not affect its ATP and DNA-binding abilities. These data allow us to identify R982 as the residue that functions as a BLM arginine finger. Our findings further indicate how the arginine finger is precisely positioned by the conserved motifs with respect to the γ-phosphate.     

Fusion expression of the PGLa-AM1 with native structure and evaluation of its anti-<Emphasis Type="Italic">Helicobacter pylori</Emphasis> activity

Helicobacter pylori (H. pylori) shows increasingly enhanced resistance to various antibiotics, and its eradication has become a major problem in medicine. The antimicrobial peptide PGLa-AM1 is a short peptide with 22 amino acids and exhibits strong antibacterial activity. In this study, we investigated whether it has anti-H. pylori activity for the further development of anti-H. pylori drugs to replace existing antibiotics. However, the natural antimicrobial peptide PGLa-AM1 shows a low yield and is difficult to separate, limiting its application. A good strategy to solve this problem is to express the antimicrobial peptide PGLa-AM1 using gene engineering at a high level and low cost. For getting PGLa-AM1 with native structure, in this study, a specific protease cleavage site of tobacco etch virus (TEV) was designed before the PGLa-AM1 peptide. For convenience to purify and identify high-efficiency expression PGLa-AM1, the PGLa-AM1 gene was fused with the polyhedrin gene of Bombyx mori (B. mori), and a 6 × His tag was designed to insert before the amino terminus of the fusion protein. The fusion antibacterial peptide PGLa-AM1 (FAMP) gene codon was optimized, and the gene was synthesized and cloned into the Escherichia coli (E. coli) pET-30a (+) expression vector. The results showed that the FAMP was successfully expressed in E. coli. Its molecular weight was approximately 34 kDa, and its expression level was approximately 30 mg/L. After the FAMP was purified, it was further digested with TEV protease. The acquired recombinant antimicrobial peptide PGLa-AM1 exerted strong anti-H. pylori activity and therapeutic effect in vitro and in vivo.     

Impacts of Cash Transfer Programs on Rural Livelihoods: a Case Study in the Brazilian Amazon Estuary

We conducted a large household survey in a region of the Amazon estuary in Brazil to investigate the dependence of small farming households on government cash transfers and to identify the main factors that lead to better livelihood outcomes. The study examined the factors that contribute to heterogeneous household livelihoods and patterns of dependence on cash transfer programs. Multinomial logistic regression was used to evaluate household attributes affecting the level of dependence on cash transfers. Results indicate that households engage in a diversity of livelihood strategies, and vary in dependence on cash transfers. Lower levels of dependency are associated with higher levels of education and income from off-farm activities as well as larger property sizes and holdings in the várzea. Recognition of the causes and potential range of dependence on cash transfer programs adds decision-making capacity for policy makers seeking avenues to reduce dependence and increase program effectiveness.