Live Transport of Crustaceans in Air - Prolonging the Survival of Crabs

We studied the live transport of crustaceans in air, using the spanner crab Ranina ranina as an example, and developed guidelines for handling live spanner crabs which we presented to an industry workshop. Our findings were also of general relevance to the live shipment of other oceanic crab species. The spanner crab fishery has burgeoned over the last couple of years through interest in the live market. The choice of spanner crabs as a topic of study was therefore timely . The handling practices used on boats in this fishery, (storing crab s out of water), were appropriate for handling "live" crabs destined for cooking but we found that more careful handling was required for the live export market. While spanner crabs appeared to tolerate being stored in air, our studies showed that this tolerance was misleading. The crabs stressed quickly when they arrived on deck and became quiescent . Their blood pH fell rapidly, a symptom called acidosis . Quiescence was their only means of dealing with acidosis. In practical terms, any time that a spanner crab was out of water was too long. Spanner crabs are stored in air twice after harvest, first while on the boat and again when actually exported . The conditions experienced by the crabs stored in air at ambient temperature on boats were much worse than those of crabs cooled for export. At the very least, the crabs should be cooled down or sprayed with cold seawater when stored in air on boats. The best way to store crabs on boats would be submerged in live wells but there are problems with this because the unrestrained crabs can injure each other. We also tested other methods of alleviating stress. Spanner crabs cannot buffer low pH in the blood, unlike many other commercially harvested crustaceans. We sought to correct this using a dip treatment . However, this did not improve their survival. For an animal that cannot correct acidosis, spanner crabs survive for an extraordinary period in air. The stressed crabs may linger on because they "shut down" and keep the acidosis from reaching fatal levels. Using the results of our research, we presented guidelines for handling spanner crabs at an industry workshop on December 9-1Oth 1993. This workshop attracted favourable comment from the industry and copies of several papers were published in the May edition of Queensland Fisherman. We concluded that the way the crabs are currently being handled on boats is too stressful. Physiological studies show that spanner crabs, like other oceanic crabs, are not well equipped to survive in air . Yet even if you store them cold on the boat they still die after a few days in tanks on shore. This mortality is an impediment to the maturity of the industry. The crabs may be succumbing to bacterial infections caused by injury and we recommend that their claws are immobilised by banding after capture

Increasing seedstock production of domesticated giant tiger prawns

Given the rationale that pond systems are likely the most cost-effective system for large-scale production of P. monodon broodstock, this project aimed to determine whether pond-rearing poses a significant risk for broodstock production. The gross reproductive development of males reared in low-density broodstock ponds was found comparable to sibling males reared in controlled-environment tanks. Furthermore,none of the environmental ‘stressors’ and dietary manipulations examined impacted on male reproductive tract development. Thus, within the boundaries of the parameters tested, we can state that rearing of male broodstock in low-density ponds does not pose inherent risks of gross reproductive tract impairment. Given the typically lower costs of constructing and managing broodstock in large-scale pond systems, as compared to smaller raceway and tank systems, the incorporation of a pond-rearing phase in broodstock production could clearly increase cost-effectiveness of broodstock production at a commercial scale

An analysis of identical single-nucleotide polymorphisms genotyped by two different platforms

The overlap of 94 single-nucleotide polymorphisms (SNP) among the 4,720 and 11,120 SNPs contained in the linkage panels of Illumina and Affymetrix, respectively, allows an assessment of the discrepancy rate produced by these two platforms. Although the no-call rate for the Affymetrix platform is approximately 8.6 times greater than for the Illumina platform, when both platforms make a genotypic call, the agreement is an impressive 99.85%. To determine if disputed genotypes can be resolved without sequencing, we studied recombination in the region of the discrepancy for the most discrepant SNP rs958883 (typed by Illumina) and tsc02060848 (typed by Affymetrix). We find that the number of inferred recombinants is substantially higher for the Affymetrix genotypes compared to the Illumina genotypes. We illustrate this with pedigree 10043, in which 3 of 7 versus 0 of 7 offspring must be double recombinants using the genotypes from the Affymetrix and the Illumina platforms, respectively. Of the 36 SNPs with one or more discrepancies, we identified a subset that appears to cluster in families. Some of this clustering may be due to the presence of a second segregating SNP that obliterates a XbaI site (the restriction enzyme used in the Affymetrix platform), resulting in a fragment too long (>1,000 bp) to be amplified

Long-term impacts of invasive species on a native top predator in a large lake system

1. Declining abundances of forage fish and the introduction and establishment of non-indigenous species have the potential to substantially alter resource and habitat exploitation by top predators in large lakes. 2. We measured stable isotopes of carbon (δ13C) and nitrogen (δ15N) in field-collected and archived samples of Lake Ontario lake trout (Salvelinus namaycush) and five species of prey fish and compared current trophic relationships of this top predator with historical samples. 3. Relationships between δ15N and lake trout age were temporally consistent throughout Lake Ontario and confirmed the role of lake trout as a top predator in this food web. However, δ13C values for age classes of lake trout collected in 2008 ranged from 1.0 to 3.9‰ higher than those reported for the population sampled in 1992. 4. Isotope mixing models predicted that these changes in resource assimilation were owing to the replacement of rainbow smelt (Osmerus mordax) by round goby (Neogobius melanostomus) in lake trout diet and increased reliance on carbon resources derived from nearshore production. This contrasts with the historical situation in Lake Ontario where δ13C values of the lake trout population were dominated by a reliance on offshore carbon production. 5. These results indicate a reduced capacity of the Lake Ontario offshore food web to support the energetic requirements of lake trout and that this top predator has become increasingly reliant on prey resources that are derived from nearshore carbon pathways

Multi-Messenger Astronomy with Extremely Large Telescopes

The field of time-domain astrophysics has entered the era of Multi-messenger Astronomy (MMA). One key science goal for the next decade (and beyond) will be to characterize gravitational wave (GW) and neutrino sources using the next generation of Extremely Large Telescopes (ELTs). These studies will have a broad impact across astrophysics, informing our knowledge of the production and enrichment history of the heaviest chemical elements, constrain the dense matter equation of state, provide independent constraints on cosmology, increase our understanding of particle acceleration in shocks and jets, and study the lives of black holes in the universe. Future GW detectors will greatly improve their sensitivity during the coming decade, as will near-infrared telescopes capable of independently finding kilonovae from neutron star mergers. However, the electromagnetic counterparts to high-frequency (LIGO/Virgo band) GW sources will be distant and faint and thus demand ELT capabilities for characterization. ELTs will be important and necessary contributors to an advanced and complete multi-messenger network.Comment: White paper submitted to the Astro2020 Decadal Surve

Genetic Analysis Workshop 14: microsatellite and single-nucleotide polymorphism marker loci for genome-wide scans

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Identifying Rare Variants from Exome Scans: The GAW17 Experience

Genetic Analysis Workshop 17 (GAW17) provided a platform for evaluating existing statistical genetic methods and for developing novel methods to analyze rare variants that modulate complex traits. In this article, we present an overview of the 1000 Genomes Project exome data and simulated phenotype data that were distributed to GAW17 participants for analyses, the different issues addressed by the participants, and the process of preparation of manuscripts resulting from the discussions during the worksho

Molecular epidemiological analysis of Escherichia coli sequence type ST131 (O25:H4) and bla CTX-M-15among extended-spectrum-β- lactamase-producing E. coli from the United States, 2000 to 2009

Escherichia coli sequence type ST131 (from phylogenetic group B2), often carrying the extended-spectrum-β-lactamase (ESBL) gene bla , is an emerging globally disseminated pathogen that has received comparatively little attention in the United States. Accordingly, a convenience sample of 351 ESBL-producing E. coli isolates from 15 U.S. centers (collected in 2000 to 2009) underwent PCR-based phylotyping and detection of ST131 and bla . A total of 200 isolates, comprising 4 groups of 50 isolates each that were (i) bla negative non-ST131, (ii) bla positive non-ST131, (iii) bla negative ST131, or (iv) bla positive ST131, also underwent virulence genotyping, antimicrobial susceptibility testing, and pulsed-field gel electrophoresis (PFGE). Overall, 201 (57%) isolates exhibited bla , whereas 165 (47%) were ST131. ST131 accounted for 56% of bla -positive-versus 35% of bla -negative isolates (