The Effect of Constant and Fluctuating Temperatures on the Confinement-induced Plasma Cortisol Stress Response in Channel Catfish lctalurus punctatus

Abstract.— Initial and confinement-induced changes of plasma cortisol were measured in channel catfish Ictalurus punctatus acclimated to upper and lower constant temperatures for each season, a spring/fall diurnal pattern between 15 and 26 C, and a summer diurnal pattern between 24 and 35 C. In diurnal treatments, temperature changes were achieved in 10 h and held constant for 2 h before reversing the temperature. Fish held in the spring/fall pattern or at a constant temperature of 15 or 26 C revealed no plasma cortisol concentration differences due to acclimation temperature, but hormone concentrations in all groups increased by about 4.5 fold following a 2-h confinement. Fish held on a summer pattern had differences in both the initial cortisol samples and those measured after confinement. Acclimation to a constant 35 C resulted in significantly higher initial cortisol concentrations, but these levels did not increase following confinement. The inability of the fish held at 35 C to respond to the confinement was thought to be due to the constant thermal stress, resulting in an inadequate interrenal reserve. Physiological consequences due to the diurnal physiochemi-cal cycling in ponds needs further attention.     

Sex-Reversal of Oreochromis aureus by Immersion in Mibolerone,a Synthetic Steroid 1

Mibolerone (MI), a synthetic steroid, was used to sex-reverse undifferentiated Oreochromis aureus fry. Fry were exposed to 0.0, 0.3, 0.6, or 1.0 ppm MI in static-water solutions for five weeks (immersion treatments) or were fed a diet containing 1.0 ppm MI for four weeks in a flow-through system. Following hormone treatment, the fish were grown to over 60 mm total length prior to sex determination using gonadal squash examination. Fish immersed in 1.0, 0.6, or 0.3 ppm MI had average tissue MI concentrations of 14.4, 5.6, and 3.3 ppm, respectively. Immersion in either 1.0 or 0.6 ppm MI for five weeks resulted in an average of 82% males and 18% ovo-testicular fish (inter-sex fish) with no gonadal females being produced. Exposure to 0.3 ppm MI resulted in 78.7% males, 20.7% ovo-testicular fish, and 0.7% gonadal females. Feeding a diet containing 1.0 ppm MI resulted in 85% males, 11% ovo-testicular fish, and 4% gonadal females. Fry growth and survival were negatively correlated with the MI concentration of the immersion treatments. Exposing tilapia fry to static-water solutions of 0.6 ppm MI for five weeks appears to be a feasible method of eliminating the production of functional females. Immersion solutions should be changed at least weekly to maintain an effective hormone concentration.     

Glyphosate-resistant horseweed made sensitive to glyphosate: low-temperature suppression of glyphosate vacuolar sequestration revealed by 31P NMR

BACKGROUND: Horseweed has been the most invasive glyphosate‐resistant (GR) weed, spreading to 16 states in the United States and found on five continents. The authors have previously reported that GR horseweed employs rapid vacuolar sequestration of glyphosate, presumably via a tonoplast transporter, substantively to reduce cytosolic glyphosate concentrations. 1 It was hypothesized that glyphosate sequestration was the herbicide resistance mechanism. If resistance is indeed endowed by glyphosate sequestration, suppression of sequestration offers the potential for controlling GR horseweed at normal herbicide field‐use rates. RESULTS: Low‐temperature ³¹P NMR experiments performed in vivo with GR cold‐acclimated horseweed showed markedly suppressed vacuolar accumulation of glyphosate even 3 days after glyphosate treatment. [In stark contrast, 85% of the visible glyphosate was sequestered 24 h after spraying warm‐acclimated GR horseweed.] Cold‐acclimated GR horseweed treated at normal use rates and maintained at low temperature succumbed to the lethal effects of glyphosate over a 40 day period. Treatment of GR horseweed in the field when temperatures were cooler showed the predicted positive herbicidal response. CONCLUSIONS: Low temperature markedly diminishes vacuolar sequestration of glyphosate in the GR horseweed biotype, yielding a herbicide response equivalent to that of the sensitive biotype. This supports the recent hypothesis 1 that glyphosate sequestration is the resistance mechanism employed by GR horseweed. Copyright © 2011 Society of Chemical Industry     

Deep-Sea Coral Garden Invertebrates and Their Associated Fungi Are Genetic Resources for Chronic Disease Drug Discovery

Chronic diseases characterized by bone and cartilage loss are associated with a reduced ability of progenitor cells to regenerate new tissues in an inflammatory environment. A promising strategy to treat such diseases is based on tissue repair mediated by human mesenchymal stem cells (hMSCs), but therapeutic outcomes are hindered by the absence of small molecules to efficiently modulate cell behaviour. Here, we applied a high-throughput drug screening technology to bioprospect a large library of extracts from Irish deep-sea organisms to induce hMSC differentiation toward musculoskeletal lineages and reduce inflammation of activated macrophages. The library included extracts from deep-sea corals, sponges and filamentous fungi representing a novel source of compounds for the targeted bioactivity. A validated hit rate of 3.4% was recorded from the invertebrate library, with cold water sea pens (octocoral order Pennatulacea), such as Kophobelemnon sp. and Anthoptilum sp., showing the most promising results in influencing stem cell differentiation toward osteogenic and chondrogenic lineages. Extracts obtained from deep-sea fungi showed no effects on stem cell differentiation, but a 6.8% hit rate in reducing the inflammation of activated macrophages. Our results demonstrate the potential of deep-sea organisms to synthetize pro-differentiation and immunomodulatory compounds that may represent potential drug development candidates to treat chronic musculoskeletal diseases.     

BOOK REVIEWS

Book reviewed in this article:
Training and Working Dogs , Scott Lithgow
Australian Sheep Dogs, Rod Cavanagh     

Effects of continuous intra-articular infusion of gentamicin on synovial membrane and articular cartilage in the tarsocrural joint of horses

OBJECTIVE: To determine the effects of a continuous intra-articular infusion of gentamicin on the synovial membrane and articular cartilage in the tarsocrural joint of horses. ANIMALS: 6 healthy adult horses. PROCEDURE: A balloon infusion system attached to a catheter placed in the plantarolateral pouch of both tarsocrural joints in each horse was used for continuous gentamicin solution (GM) or balanced electrolyte solution (BES) delivery for 5 days. Cartilage and synovial membrane specimens were collected on day 5 from 3 horses and on day 14 from the remaining 3 horses. Both infused joints from each horse were assessed, using gross evaluation and histologic scoring systems. RESULTS: Significant differences in the histologic scores of synovial membrane specimens between the GM- and BES-treated joints at either 5 or 14 days were not observed. Safranin-O-fast green staining scores were similar between cartilage specimens from GM- and BES-treated joints. Although the synovial membrane histologic scores and safranin-O-fast green staining scores improved from day 5 to 14, the changes in scores were not significant. Loss of synovial intimal cells from villi was found more commonly in sections of synovial membrane from GM-treated joints, compared with BES-treated joints. CONCLUSIONS AND CLINICAL RELEVANCE: Continuous infusion of GM into the tarsocrural joint of horses does not have significant effects on histologic scores of articular cartilage or synovial membrane, compared with those infused with BES. Continuous infusion of GM into the tarsocrural joint of horses for 5 days is an acceptable method for the treatment of septic arthritis.