Preparing for a changing future in recreational fisheries: 100 research questions for global consideration emerging from a horizon scan

Reviews in Fish Biology and Fisheries - Recreational fisheries hold immense ecological, social, and economic value. The management of these fisheries is increasingly important as we move forward in...     

Synthesis and characterization of diethyltin-based three dimensional self-assemblies derived from sulfonate-phosphonate ligands

Diethyltin(methoxy)methanesulfonate reacts readily with equimolar amount of t-butylphosphonic acid (RT, 8-10 h) in moist dichloromethane and methanol to afford [(Et₂Sn)₆(O₃PBu^t)₄(OSO₂Me)₄·CH₂Cl₂]_n (1) and [(Et₂Sn)₆(O₃PBu^t)₄(OSO₂Me)₄·2H₂O]_n (2), respectively. The identity of these compounds has been established by IR, multinuclear (¹H, ¹³C, ³¹P and ¹¹⁹Sn) NMR as well as X-ray crystallographic studies. Despite apparent similarity in the composition, a marked difference in the structural motifs between 1 and 2 is evident in the solid state. For 1, the formation of three-dimensional self- assembly results from μ₃-phosphonate and μ₂, μ₃-sulfonate binding modes and exhibits continuous channel of voids which are occupied by disordered CH₂Cl₂ molecules. In contrast, the sulfonate ligands in 2 act exclusively in μ₂-fashion and hydrogen bonding interactions (O-H?O) between coordinated water molecules and methanesulfonate groups is significant in the construction of 3D supramolecular assembly.     

Alternative coreceptor requirements for efficient CCR5- and CXCR4-mediated HIV-1 entry into macrophages

Macrophage tropism of human immunodeficiency virus type 1 (HIV-1) is distinct from coreceptor specificity of the viral envelope glycoproteins (Env), but the virus-cell interactions that contribute to efficient HIV-1 entry into macrophages, particularly via CXCR4, are not well understood. Here, we characterized a panel of HIV-1 Envs that use CCR5 (n = 14) or CXCR4 (n = 6) to enter monocyte-derived macrophages (MDM) with various degrees of efficiency. Our results show that efficient CCR5-mediated MDM entry by Env-pseudotyped reporter viruses is associated with increased tolerance of several mutations within the CCR5 N terminus. In contrast, efficient CXCR4-mediated MDM entry was associated with reduced tolerance of a large deletion within the CXCR4 N terminus. Env sequence analysis and structural modeling identified amino acid variants at positions 261 and 263 within the gp41-interactive region of gp120 and a variant at position 326 within the gp120 V3 loop that were associated with efficient CXCR4-mediated MDM entry. Mutagenesis studies showed that the gp41 interaction domain variants exert a significant but strain-specific influence on CXCR4-mediated MDM entry, suggesting that the structural integrity of the gp120-gp41 interface is important for efficient CXCR4-mediated MDM entry of certain HIV-1 strains. However, the presence of Ile326 in the gp120 V3 loop stem, which we show by molecular modeling is located at the gp120-coreceptor interface and predicted to interact with the CXCR4 N terminus, was found to be critical for efficient CXCR4-mediated MDM entry of divergent CXCR4-using Envs. Together, the results of our study provide novel insights into alternative mechanisms of Env-coreceptor engagement that are associated with efficient CCR5- and CXCR4-mediated HIV-1 entry into macrophages.     

Comparative analyses between lolium/festuca introgression lines and rice reveal the major fraction of functionally annotated gene models is located in recombination-poor/very recombination-poor regions of the genome

Publication of the rice genome sequence has allowed an in-depth analysis of genome organization in a model monocot plant species. This has provided a powerful tool for genome analysis in large-genome unsequenced agriculturally important monocot species such as wheat, barley, rye, Lolium, etc. Previous data have indicated that the majority of genes in large-genome monocots are located toward the ends of chromosomes in gene-rich regions that undergo high frequencies of recombination. Here we demonstrate that a substantial component of the coding sequences in monocots is localized proximally in regions of very low and even negligible recombination frequencies. The implications of our findings are that during domestication of monocot plant species selection has concentrated on genes located in the terminal regions of chromosomes within areas of high recombination frequency. Thus a large proportion of the genetic variation available for selection of superior plant genotypes has not been exploited. In addition our findings raise the possibility of the evolutionary development of large supergene complexes that confer a selective advantage to the individual.     

Distribution of megaplasmids in Lactobacillus salivarius and other lactobacilli

The genome of Lactobacillus salivarius UCC118 includes a 242-kb megaplasmid, pMP118. We now show that 33 strains of L. salivarius isolated from humans and animals all harbor a megaplasmid, which hybridized with the repA and repE replication origin probes of pMP118. Linear megaplasmids that did not hybridize with the pMP118 repA probe were also found in some strains of L. salivarius, showing for the first time that a lactic acid bacterium has multiple megaplasmids. Phylogenetic analysis of the repE and groEL sequences of 28 L. salivarius strains suggested similar evolutionary paths for the chromosome and megaplasmid. Although the replication origin of circular megaplasmids in L. salivarius was highly conserved, genotypic and phenotypic comparisons revealed significant variation between megaplasmid-encoded traits. Furthermore, megaplasmids of sizes ranging from 120 kb to 490 kb were present in seven strains belonging to six other Lactobacillus species from among 91 strains and 47 species tested. The discovery of the widespread presence of megaplasmids in L. salivarius, and restricted carriage by other Lactobacillus species, provides an opportunity to study the contribution of large extrachromosomal replicons to the biology of Lactobacillus.     

Extreme dives by free-ranging emperor penguins

We examined the incidence of extreme diving in a 3-year overwintering study of emperor penguins Aptenodytes forsteri in East Antarctica. We defined extreme dives as very deep (> 400 m) and/or very long (> 12 min). Of 137364 dives recorded by 93 penguins 264 dives reached depths > 400 m and 48 lasted > 12 min. Most (65%) very long dives occurred in winter (May–August) while 83% of the very deep dives took place in spring (September–November). The two most extreme dives (564 m depth, 21.8 min duration) were separate dives and were performed by different individual penguins. Penguins diving extremely deeply may have done so as part of their foraging strategy whereas penguins diving for very long times may have been forced to do so by changes in the sea-ice conditions.     

The reaction mechanism of the Ga(III)Zn(II) derivative of uteroferrin and corresponding biomimetics

Purple acid phosphatase from pig uterine fluid (uteroferrin), a representative of the diverse family of binuclear metallohydrolases, requires a heterovalent Fe(III)Fe(II) center for catalytic activity. The active-site structure and reaction mechanism of this enzyme were probed with a combination of methods including metal ion replacement and biomimetic studies. Specifically, the asymmetric ligand 2-bis{[(2-pyridylmethyl)-aminomethyl]-6-[(2-hydroxybenzyl)(2-pyridylmethyl)]aminomethyl}-4-methylphenol and two symmetric analogues that contain the softer and harder sites of the asymmetric unit were employed to assess the site selectivity of the trivalent and divalent metal ions using (71)Ga NMR, mass spectrometry and X-ray crystallography. An exclusive preference of the harder site of the asymmetric ligand for the trivalent metal ion was observed. Comparison of the reactivities of the biomimetics with Ga(III)Zn(II) and Fe(III)Zn(II) centers indicates a higher turnover for the former, suggesting that the M(III)-bound hydroxide acts as the reaction-initiating nucleophile. Catalytically active Ga(III)Zn(II) and Fe(III)Zn(II) derivatives were also generated in the active site of uteroferrin. As in the case of the biomimetics, the Ga(III) derivative has increased reactivity, and a comparison of the pH dependence of the catalytic parameters of native uteroferrin and its metal ion derivatives supports a flexible mechanistic strategy whereby both the mu-(hydr)oxide and the terminal M(III)-bound hydroxide can act as nucleophiles, depending on the metal ion composition, the geometry of the second coordination sphere and the substrate.     

Abnormal function and glucose metabolism in the type-2 diabetic db/db mouse heart

This study examined cardiac function and glucose metabolism in the 6-month-old db/db mouse, a model of type-2 diabetes. Cine magnetic resonance spectroscopy (MRI) was used to measure cardiac function in vivo. The db/db mice had decreased heart rates (17%, p<0.01) and stroke volumes (21%, p<0.05) that resulted in lower cardiac output (35%, p<0.01) than controls. Although there was no difference in ejection fraction between the 2 groups, db/db mouse hearts had a 35% lower maximum rate of ejection (p<0.01) than controls. In a protocol designed to assess maximal insulin-independent glucose uptake, hearts were isolated and perfused in Langendorff mode and subjected to 0.75 mL.min(-1).(g wet mass)(-1) low flow ischemia for 32 min. Glucose uptake during ischemia was 21% lower than in controls, and post-ischemic recovery of cardiac function was decreased by 30% in db/db mouse hearts (p<0.05). Total cardiac GLUT 4 protein was 56% lower (p<0.01) in db/db mice than in controls. In summary, the db/db mouse has abnormal left ventricular function in vivo, with impaired glucose uptake during ischemia, leading to increased myocardial damage.     

Drought intensification alters the composition,body size,and trophic structure of invertebrate assemblages in a stream mesocosm experiment

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