Population genetic divergence of bonnethead sharks Sphyrna tiburo in the western North Atlantic: Implications for conservation

1. Sharks are a priority for conservation because numerous species, including small-sized coastal species, are being heavily exploited by commercial and recreational fisheries. Understanding the genetic population structure of sharks is key to effective management, maximizing their evolutionary potential in a rapidly changing environment and preventing population declines.
2. Limited dispersal is an important factor promoting population divergence for several coastal shark species. The genetic variation in 14 microsatellite loci and 21,006 single nucleotide polymorphisms genotyped using restriction-site-associated DNA sequencing was analysed to assess the genetic structure of the bonnethead shark, Sphyrna tiburo, in the western North Atlantic.
3. Genetic differences were identified among three well-defined regions: the western Florida coast, the south-eastern US Atlantic coast, and the southern Gulf of Mexico. Results support previous studies based on mitochondrial DNA sequences in defining differences among these regions and suggest limitations of bonnethead sharks in routinely performing long-distance migrations.
4. The limited connectivity among regions explains the pattern of genetic divergence but also reported divergence at the species/subspecies level. These genetically discrete bonnethead populations have independent evolutionary histories that may include local adaptations to specific areas.
5. Bonnethead sharks are currently managed as two stocks in the USA owing to recent genetic, tagging, and life history studies; however, no stock assessments or management plans exist for Mexico. These results not only serve to reinforce US management strategies and provide critical data about the extent of gene flow and sex dispersal among populations, but also begin the process of effective management in the waters of Mexico to ensure the long-term productivity and resilience of this species. With an absence of gene flow between populations from US waters and the southern Gulf of Mexico, there is a need for management plans based upon independent biological and population dynamics data since limited or no opportunities for populations to interchange individuals may occur to re-establish population viability.

     

Biosynthesis of Polyunsaturated Fatty Acids in Marine Invertebrates: Recent Advances in Molecular Mechanisms

Virtually all polyunsaturated fatty acids (PUFA) originate from primary producers but can be modified by bioconversions as they pass up the food chain in a process termed trophic upgrading. Therefore, although the main primary producers of PUFA in the marine environment are microalgae, higher trophic levels have metabolic pathways that can produce novel and unique PUFA. However, little is known about the pathways of PUFA biosynthesis and metabolism in the levels between primary producers and fish that are largely filled by invertebrates. It has become increasingly apparent that, in addition to trophic upgrading, de novo synthesis of PUFA is possible in some lower animals. The unequivocal identification of PUFA biosynthetic pathways in many invertebrates is complicated by the presence of other organisms within them. These organisms include bacteria and algae with PUFA biosynthesis pathways, and range from intestinal flora to symbiotic relationships that can involve PUFA translocation to host organisms. This emphasizes the importance of studying biosynthetic pathways at a molecular level, and the continual expansion of genomic resources and advances in molecular analysis is facilitating this. The present paper highlights recent research into the molecular and biochemical mechanisms of PUFA biosynthesis in marine invertebrates, particularly focusing on cephalopod molluscs.     

Investigation of the Link between Broodstock Infection,Vertical Transmission,and Prevalence of Flavobacterium psychrophilum in Eggs and Progeny of Rainbow Trout and Coho Salmon

Abstract

The etiological agent of bacterial coldwater disease (BCWD), Flavobacterium psychrophilum, can be transmitted both vertically and horizontally. Outbreaks of BCWD can result in significant losses in salmonid aquaculture. Reduction of outbreaks in fry may be possible through implementation of a management strategy in which progeny of heavily infected broodstock are culled from the general population. Diagnostic assays to quantify F. psychrophilum concentrations in tissue samples and confirm presence of the bacterium in ovarian fluid have been previously validated. In the current study, these assays were used to screen 60 female Rainbow Trout Oncorhynchus mykiss and 60 female Coho Salmon O. kisutch broodstock at two aquaculture facilities. Eyed eggs from 10 female broodstock (five fish from each facility) exhibiting graded levels of infection were transferred to the University of Idaho and monitored through early life stages for the presence of F. psychrophilum. Female Rainbow Trout broodstock were not positive for F. psychrophilum by enzyme-linked immunosorbent assay (ELISA) and prevalence was low in these progeny. However, ELISA optical density values for kidney correlated to F. psychrophilum prevalence in progeny (r = 0.938, P < 0.05) of Coho Salmon. Nested PCR on ovarian fluid was not a reliable indicator of vertical transmission in either species as broodstock ovarian fluid results did not correlate to F. psychrophilum prevalence in eyed eggs. Further research with these assays is necessary; however, results from this study indicate that broodstock screening may be a potential tool for evaluating F. psychrophilum infection levels, which could become an important component for disease management.

Received December 19, 2012; accepted December 8, 2013     

Adding microencapsulated pear ester to insecticides for control of Cydia pomonella (Lepidoptera: Tortricidae) in apple

BACKGROUND: The possibility of improving the efficacy of various insecticides for codling moth, Cydia pomonella (L.), by the addition of a microencapsulated formulation of pear ester, ethyl (2E, 4Z)‐2,4‐decadienoate (PE‐MEC, 5% AI), was evaluated in field trials in apple from 2005 to 2009. RESULTS: The addition of PE‐MEC (<3.0 g AI ha^?1) significantly lowered fruit injury with low rates of organophosphate and neonicotinoid insecticides. The addition of PE‐MEC (1.48 g AI ha^?1) to maximum label rates of insecticides with moderate activity for codling moth, such as ebamectin benzoate, spinosad and methoxyfenozide, significantly improved their effectiveness. However, PE‐MEC did not consistently improve the activity of maximum label rates of either rynaxypyr or spinetoram. The addition of PE‐MEC with seasonal spray programs of acetamiprid and azinphos‐methyl in combination with the use of sex pheromones for mating disruption provided the most effective control. CONCLUSION: The addition of PE‐MEC can improve the effectiveness of some insecticides for codling moth in apple. Insecticides active via dermal toxicity are more strongly improved by the addition of PE‐MEC. Season‐long use of PE‐MEC can also augment the effectiveness of mating disruption. Adding PE‐MEC to variable integrated management programs for C. pomonella should be further investigated. Published 2012 by John Wiley & Sons, Ltd.     

Controlled wound repair in guinea pigs, using antimicrobials that alter fibroplasia

The repair processes of incised wounds depend, in part, on fibroplasia induced by soluble mediators from monocytic macrophages. Two topical antimicrobials were evaluated, each of which effectively controlled wound sepsis and yet each had widely different effects on fibroplasia and wound strength. Paired-incision dermal wounds on the flanks of guinea pigs were treated with a substance containing reactive chlorine (Alcide) or with a compound that is a mixture of two surfactants. One side of each guinea pig was treated with one of the antimicrobials (treated wounds); the opposite side was treated with isotonic saline solution (control wounds). At 7, 10, and 16 days after surgery, tensiometric measurements of C31G (a surfactant)-treated wounds were 99%, 139%, and 195% of control wound values, respectively. Alcide-treated wounds were 76%, 58%, and 88% of control wounds, respectively. Wounds treated with chlorhexidine had reduced strength at 7 days (73%) and at 10 days (78%), but by 14 days, they were similar to control wounds (94%). The main difference between the wounds was the amount of collagen formation. Alcide-treated wounds incorporated less than 50% of the amount of 14C-proline than did the wounds treated with C31G. However, Alcide-treated wounds epithelialized as rapidly as did control wounds, and had minimal scar formation. Microscopic evaluations indicated greatly reduced inflammatory infiltrates in Alcide-treated wounds, indicating that reduced wound strength may be associated with lack of fibroblast-stimulating activity by monocytes.     

Platelet Dysfunction Associated With Immune-Mediated Thrombocytopenia in Dogs

The effect of antiplatelet antibody on in vitro platelet function was investigated in 15 dogs with immune-mediated thrombocytopenia (ITP). Platelet aggregation was assessed after addition of serum from healthy dogs (n = 5) or dogs with ITP (n = 15) to platelet-rich plasma from a healthy donor dog. The aggregation responses to adenosine diphosphate, thrombin, and collagen/epinephrine were measured as the maximum aggregation observed after 2 minutes. In 13 of 15 dogs with ITP, maximal aggregation was significantly inhibited in response to ADP, thrombin, or collagen/epinephrine. The slope of the aggregation curve was decreased after addition of serum from 9 of 15 patients. A polyclonal rabbit anti—dog platelet antiserum induced inhibition of aggregation with all 3 agonists.
Serum from control dogs neither inhibited nor activated platelet aggregation. Aggregation experiments were repeated with all 3 agonists after addition of patient immunoglobulin (lg)G or IgG from a healthy dog to platelet-rich plasma. The IgG fraction from 9 of 10 dogs with ITP suppressed platelet aggregation. The IgG fraction from polyclonal rabbit anti—dog platelet antiserum inhibited platelet aggregation with all agonists. These results suggest that many canine ITP patients have circulating antibodies that, in addition to causing platelet destruction, may cause platelet dysfunction.     

Equine immune-mediated hemolytic anemia associated with Clostridium perfringens infection

Background: Previous studies have suggested an association between equine immune-mediated hemolytic anemia and clostridial infections or neck abscesses.
Objective: The purpose of this report was to describe and characterize the hematologic abnormalities in a horse with Clostridium -associated immune-mediated hemolytic anemia. We also retrospectively evaluated hematologic abnormalities in 8 horses with clostridial myositis or subcutaneous emphysema.
Methods: A 7-year-old Foreign Warm-Blood gelding was evaluated for anemia and a cervical abscess. CBCs and reticulocyte counts were obtained using an Advia 120 analyzer and evaluation of Wright's-stained smears. All cases of equine Clostridium spp. myositis or subcutaneous emphysema over a 7-year period were identified in a retrospective search of the University of Minnesota Veterinary Teaching Hospital database. Clinical, hematologic, and microbiological findings were recorded.
Results: Clostridium perfringens genotype A was isolated from the neck wound of the gelding. The CBC was characterized by severe regenerative anemia, intravascular hemolysis, and RBC agglutination. A direct Coombs' test was positive. Moderate numbers of spheroechinocytes were observed. The total automated reticulocyte count was 4.5% (56,700/μL), with most reticulocytes having low absorbance (mature reticulocytes). The anemia responded to penicillin and steroidal and nonsteroidal immunosuppressive drugs. Of 8 horses with myositis, all of which involved the cervical region, 5 were anemic, 1 had a positive direct Coombs' test, and 2 had increased numbers of type III echinocytes and spheroechinocytes.
Conclusions: The presence of type III echinocytes or spheroechinocytes may be helpful in diagnosing immune-mediated hemolytic anemia associated with clostridial infections in horses. Automated reticulocyte counts may detect very low levels of reticulocytosis in hemolytic anemia in horses.