Importance of various marine coastal habitats during the life cycle of Spratelloides delicatulus in Con Dao,the oldest MPA in Vietnam

• 1. Marine protected areas (MPAs) are set up to conserve biodiversity, but their design is not always based on strictly scientific considerations. Ideally, an MPA should protect all key habitats necessary for a marine species to complete its life cycle. The identification of these key habitats is complex, especially during the early life of marine fishes.
• 2. A widely distributed tropical and important low trophic‐level fish species, Spratelloides delicatulus (Clupeidae), was used to evaluate the significance of various coastal habitats for its larvae and juveniles in the Con Dao Archipelago MPA in Vietnam. Early stages (larvae and juveniles) were sampled monthly over one year (June 2016 to May 2017) using light traps in three main habitats (seagrass beds, coral reefs and harbour). The species was identified using morphometry and DNA barcoding. Age and growth variables were estimated using otolith daily growth increments.
• 3. A total of 3,581 fish were caught. The species was not found in captures between January and February, directly linked to the decrease in seawater temperature and was most abundant from April to June. For a subsample of 248 fish (7–38 mm standard length), ages ranged from 7 to 108 days.
• 4. Captures and back‐calculated birthdates using otolith daily increments showed that S. delicatulus spawns during the period of high seawater temperature, from March to October. The species colonizes all three habitats during the early stages (0–26 days old), with growth rate lowest on the seagrass beds. Nevertheless, the species occupies seagrass beds exclusively during the older stages.
• 5. The conservation of seagrass beds in the Con Dao archipelago is essential for protection of juvenile stages of this species but this habitat is presently not included in the MPA patches. Establishment of a continuum of protected areas linking habitats, rather than the existing patches is needed to conserve the complete life cycle of this species in the Con Dao MPA.

     

Preparation of oligoalginate plant growth promoter by γ irradiation of alginate solution containing hydrogen peroxide

Degraded alginate compounds with molecular weights of 7-26, 40-77, or 11-26 kDa were obtained by γ irradiation, hydrogen peroxide (5% H(2)O(2)) treatment, or a combination treatment involving ionizing radiation and H(2)O(2), respectively. The 14 kDa oligoalginate, prepared by the combined method, promoted the growth of mustard greens and lettuce at an optimal concentration of 75 mg/L. The growth promotion effects of the oligoalginate prepared by γ irradiation in the presence of H(2)O(2) were statistically equivalent to those of the oligoalginate prepared by γ irradiation only. The combination of γ irradiation and H(2)O(2) reduced the required irradiation dosage by a factor of 9 relative to the oligoalginate produced by γ irradiation only. The combination treatment (γ irradiation/H(2)O(2)) may be carried out on a large scale at low cost to produce oligoalginate for use as a plant growth promoter in agricultural industries.     

The effect of feed pigment type on flesh pigment deposition and colour in farmed Atlantic salmon, Salmo salar L.

The characteristic pink colour of salmonid flesh is a result of deposition of naturally occurring carotenoid pigments. Achieving successful pigmentation in farmed salmonids is a vital aspect of fish farming and commercial feed production. Currently commercial diets for farmed salmonids contain either or both of the synthetic pigments commercially available, astaxanthin and canthaxanthin. Atlantic salmon, Salmo salar L. ( = 220 g initial weight) were given feeds where the pigment source was astaxanthin only, canthaxanthin only or a astaxanthin/canthaxanthin mix. The rearing environment was 12 × 3 m tanks supplied with sea water at the EWOS research farm Lønningdal, near Bergen, Norway. As the proportion of dietary canthaxanthin increased, flesh pigment levels also showed an increase; the pigment content in the muscle of canthaxanthin‐only fed fish was 0.4 mg kg^?1 (or 14%) higher than that of the astaxanthin‐only fed fish, with the mixed pigment fed fish being intermediate between the two extremes. Results of cross‐section assessment for Minolta colorimeter redness (a*) values and Roche Salmofan^TM scores also showed an increase in colour with increasing proportions of canthaxanthin in the feed. The data reported clearly indicates that S. salar ( = 810 g final weight) of this size deposit canthaxanthin more efficiently than they do astaxanthin. These results contrast with those obtained by other authors with rainbow trout, Oncorynchus mykiss (Walbaum), and imply that the absorption or utilization of the pigments differs between species.     

In vivo studies on suppressor lymphocyte activity following administration of Escherichia coli O138 lipopolysaccharide.

Evaluation of Escherichia coli vaccines used in veterinary practice usually relates to antibody formation and neglects the essential characteristics of cell function leading to this end. This paper attempts to investigate the cellular responses to E coli O138 lipopolysaccharide (LPS) administered subcutaneously in a dose range of 1 microgram to 200 microgram. Rosette-forming cell responses in the draining lymph node varied from antigenic at 10 microgram to tolerogenic at 200 microgram. The tolerogenic dose also caused a marked mitogenic response as can be seen by a fourfold increase in total lymph node cells. Fractionation of normal or LPS-responding, or LPS-tolerised lymph node cells into B cell-rich and T cell-rich fractions was carried out and these were adoptively transferred simultaneously with an antigenic dose of sheep erythrocytes (SRBC) into syngeneic recipient mice. Suppressor activity of the anti-SRBC response was found after transfer of 1 X 10(6) normal B cell fractions, 1 X 10(6) tolerised B cell fractions and 1 X 10(6) tolerised T cell fractions. LPS-antigenically stimulated lymph node cell fractions had no suppressor effect but when given with Freund's complete adjuvant ensuing T cell-rich fractions produced immunosuppression in recipient mice. The significance of these findings is discussed in relation to polyclonal B cell activation, helper and suppressor T cells, and possible feedback mechanisms between interacting subpopulations of lymph node cells.     

Retrospective study of the effect of intra-articular treatment of osteoarthritis of the distal tarsal joints in 51 horses

Osteoarthritis of the distal tarsal joints, affecting the centrodistal and tarsometatarsal joints, is a common cause of hindlimb lameness in horses. This paper describes the outcome of the intra-articular treatment of 51 horses with the condition with either methylprednisolone acetate (mpa) or triamcinolone acetonide (tr), either with or without hyaluronic acid (ha). The outcome was assessed in terms of the changes in the horses' grade of lameness. Follow-up information was obtained from the owners by means of a telephone questionnaire. Horses treated once with mpa or tr, either with or without ha, improved after a median of 56 days (P<0.0001), and there was no significant difference between mpa and tr. There was no significant further improvement in the horses treated twice. In the horses in which there was a diffuse increase in the uptake of a radiopharmaceutical by the distal tarsal joints, identified by scintigraphy, the lameness tended to improve (P=0.032), whereas in the horses in which the uptake was focal, it did not. At telephone follow-up 13 of 34 horses were reported to have had a positive outcome, but the outcome in the other 21 was reported to have been negative.     

Trapping efficacy of Duddingtonia flagrans against Haemonchus contortus at temperatures existing at lambing in Australia

The aim of this study was to determine the trapping efficacy of Duddingtonia flagrans against Haemonchus contortus at the temperature ranges experienced around lambing in the major sheep producing regions of Australia. Faeces were collected from Merino wethers, maintained in an animal house and which had received either D. flagrans chlamydospores for a 6-day period (DF) or not (NIL). Faeces were incubated at one of four daily temperature regimens which were composed of hourly steps to provide 6-19 degrees C, 9-25 degrees C, 14-34 degrees C and 14-39 degrees C to mimic normal diurnal air temperature variation. Enumeration of the number of preinfective and infective larvae that had migrated from or remained in faecal pellets was used to calculate percentage recovery and trapping efficacy of D. flagrans. Recovery of H. contortus larvae of both stages was significantly lower in DF faeces but the magnitude of the effect was considerably greater for infective larvae. Mean recovery of infective larvae from NIL and DF faeces was 10.6 and 0.4%, respectively, indicating a mean trapping efficacy of 96.4%. The lowest trapping efficacy (80.7%) was observed at 6-19 degrees C but total recovery of infective larvae, from DF faeces, was greatest at the two highest temperature regimens, although still less than 0.9%. The results of this study indicate that typical Australian lambing temperatures should not be a barrier to the use of D. flagrans as an effective biocontrol of H. contortus in Australia.     

Characteristics of extended-spectrum cephalosporin-resistant Escherichia coli and Klebsiella pneumoniae isolates from horses

The aim of the present study was to contribute to the knowledge on extended-spectrum beta-lactamases (ESBL's), AmpC beta-lactamases and integrons in Enterobacteriaceae isolated from horses, which is still limited. The susceptibility of 1581 clinical isolates from animals to ceftiofur was tested. Most of these isolates (n=1347) originated from horses. Seven ceftiofur-resistant equine isolates (four Escherichia coli and three Klebsiella pneumoniae) were identified and all seven were multidrug-resistant. These isolates were further studied for the presence of ESBL's, AmpC beta-lactamases and class 1 integrons. The potential for the horizontal transfer of resistance genes among these clinical isolates was also studied. ESBL-type resistance genes were found in five isolates, AmpC-type genes in one isolates and integrons in six isolates. Nucleotide sequence analysis revealed that the isolates carried the bla(CTX-M-1), bla(CMY-2), bla(TEM-1) and/or bla(SHV-1) genes. This is the first report describing the in vitro conjugal transfer of the bla(CTX-M-1) genes from a clinical E. coli isolate to Salmonella isolates. Gene cassettes encoding resistance to aminoglycosides (aadA1, aadA2 and aadA5), and trimethoprim (dfrA1, drfA12 and dfrA17) were found on the integrons present in the isolates. The cassette arrays of the dfrA17-aadA5 and dfrA1-aadA1 genes in the two integrons of a single E. coli isolate have not yet been described before. To our knowledge this is the first report on ESBL's and AmpC beta-lactamases in equine E. coli and Klebsiella isolates.