Characterization of genome-wide microsatellite markers in rabbitfishes,an important resource for artisanal fisheries in the Indo-West Pacific

Rabbitfishes are reef-associated fishes that support local fisheries throughout the Indo-West Pacific region. Sound management of the resource requires the development of molecular tools for appropriate stock delimitation of the different species in the family. Microsatellite markers were developed for the cordonnier, Siganus sutor, and their potential for cross-amplification was investigated in 12 congeneric species. A library of 792 repeat-containing sequences was built. Nineteen sets of newly developed primers, and 14 universal finfish microsatellites were tested in S. sutor. Amplification success of the 19 Siganus-specific markers ranged from 32 to 79% in the 12 other Siganus species, slightly decreasing when the genetic distance of the target species to S. sutor increased. Seventeen of these markers were polymorphic in S. sutor and were further assayed in S. luridus, S. rivulatus, and S. spinus, of which respectively 9, 10 and 8 were polymorphic. Statistical power analysis and an analysis of molecular variance showed that subtle genetic differentiation can be detected using these markers, highlighting their utility for the study of genetic diversity and population genetic structure in rabbitfishes.     

Laminar distribution of the cells of origin of the spinocerebral pathways involved in nociceptive transmission and pain modulation in the rat

The laminar distribution of spinomesencephalic, spinothalamic, and spinotelencephalic tract neurons, and the pattern of axonal collateralization in these spinocerebral pathways were studied in the rat by means of retrograde double-labelling of the cells with fluorescent dyes Fluoro-Gold and Primuline O. We found that sources of spinocerebral pathways to the analgesic brainstem centers, as well to thenucl. accumbens and septal nuclei, were mixed together in the marginal zone (lamina I, by Rexed), in the deep dorsal horn (laminae IV–VI), in the area around the central canal (lamina X), and within the lateral spinal nucleus. At the same time, all the above pathways retain their own specific projection fields. Thus, these spinocerebral projections could be characterized as extensive, but not diffuse. We propose that the main effect of activation of the direct spinal inputs to the limbic system is an increase in nociceptive sensitivity, but not a suppression of nocicptive transmission at the the spinal cord level.Neirofiziologiya/Neurophysiology, Vol. 28, No. 2/3, pp. 141–150, March–June, 1996.     

Activity and Differential Induction of Chitinase Isozymes in Soybean Cultivars Resistant or Susceptible to Root-knot Nematodes

Host physiological events in relation to infestation by parasitic nematodes are not well documented. Soybean plant responses to Meloidogyne incognita infestation were compared to resistant (Bryan) and susceptible (Brim) cultivars at 0, 1, 3, 10, 20, and 34 days after infestation (DAI). The resistant cultivar had higher chitinase activity than the susceptible cultivar at every sample time beginning at 3 DAI. Results from isoelectric focusing gel electrophoresis analyses indicated that three acidic chitinase isozymes with isoelectric points (pIs) of 4.8, 4.4, and 4.2 accumulated to a greater extent in the resistant compared to the susceptible cultivar following challenge. SDS-PAGE analysis of root proteins revealed that two proteins with molecular weights of approximately 31 and 46 kD accumulated more rapidly and to a higher level in the resistant than in the susceptible cultivar. Additionally, three major protein bands (33, 22, and 20 kD) with chitinase activity were detected with a modified SDS-PAGE analysis in which glycolchitin was added into the gel matrix. These results indicate that higher chitinase activity and early induction of specific chitinase isozymes may be associated with resistance to root-knot nematode in soybean.     

Insect feeding on cucumber mediated by rhizobacteria-induced plant resistance

Select strains of plant growth-promoting rhizobacteria (PGPR) were evaluated in greenhouse experiments with cucumber for induction of resistance against cucumber beetle (Diabrotica undecimpunctata howardi Barber) feeding and the beetle-transmitted cucurbit wilt disease. When beetles were given a choice between PGPR-treated and nontreated cucumber, their feeding on stems and cotyledons and the severity of wilt symptoms were significantly lower on PGPR-treated plants. HPLC analysis demonstrated that cotyledons from PGPR-treated plants contained significantly lower concentrations of the cucumber beetle feeding stimulant cucurbitacin than nontreated plants. These results suggest that a mechanism for PGPR-induced resistance against cucumber beetle feeding may involve a change in the metabolic pathway for cucurbitacin synthesis.     

Ingestion of the anti‐bacterial agent,gemifloxacin mesylate,leads to increased gst activity and peroxidation products in hemolymph of Galleria mellonella l. (lepidoptera: pyralidae)

Gemifloxacin mesylate (GEM) is a synthetic, fourth‐generation fluoroquinolone antibacterial antibiotic that has a broad spectrum of activity against bacteria. GEM inhibits DNA synthesis by inhibiting DNA gyrase and topoisomerase IV activities. Recent research into insect nutrition and mass‐rearing programs, in which antibiotics are incorporated into the culture media to maintain diet quality, raised a question of whether clinical antibiotics influence the health or biological performance of the insects that ingest these compounds. Because some antibiotics are pro‐oxidant compounds, we addressed the question with experiments designed to assess the effects of GEM (mesylate salt) on oxidative stress indicators, using Galleria mellonella larvae. The insects were reared from first‐instar larvae to adulthood on artificial diets amended with GEM at 0.001, 0.01, 0.1, or 1.0%. Feeding on the 1% diets led to significantly increased hemolymph contents of the lipid peroxidation product, malondialdehyde and protein oxidation products, protein carbonyl. All GEM concentrations led to increased hemolymph glutathione S‐transferase activity. We inferred that although it was not directly lethal to G. mellonella larvae, dietary exposure to GEM exerts measurable oxidative damage, possibly on insects generally. Long‐term, multigenerational effects remain unknown.     

Ibuprofen Blunts Ventilatory Acclimatization to Sustained Hypoxia in Humans

Ventilatory acclimatization to hypoxia is a time-dependent increase in ventilation and the hypoxic ventilatory response (HVR) that involves neural plasticity in both carotid body chemoreceptors and brainstem respiratory centers. The mechanisms of such plasticity are not completely understood but recent animal studies show it can be blocked by administering ibuprofen, a nonsteroidal anti-inflammatory drug, during chronic hypoxia. We tested the hypothesis that ibuprofen would also block the increase in HVR with chronic hypoxia in humans in 15 healthy men and women using a double-blind, placebo controlled, cross-over trial. The isocapnic HVR was measured with standard methods in subjects treated with ibuprofen (400mg every 8 hrs) or placebo for 48 hours at sea level and 48 hours at high altitude (3,800 m). Subjects returned to sea level for at least 30 days prior to repeating the protocol with the opposite treatment. Ibuprofen significantly decreased the HVR after acclimatization to high altitude compared to placebo but it did not affect ventilation or arterial O₂ saturation breathing ambient air at high altitude. Hence, compensatory responses prevent hypoventilation with decreased isocapnic ventilatory O₂-sensitivity from ibuprofen at this altitude. The effect of ibuprofen to decrease the HVR in humans provides the first experimental evidence that a signaling mechanism described for ventilatory acclimatization to hypoxia in animal models also occurs in people. This establishes a foundation for the future experiments to test the potential role of different mechanisms for neural plasticity and ventilatory acclimatization in humans with chronic hypoxemia from lung disease.     

Capillary electrophoresis of methotrexate polyglutamates and its application in evaluation of γ-glutamyl hydrolase activity

A rapid and sensitive procedure for the separation of methotrexate (MTX) polyglutamates² using capillary electrophoresis (CE) is described as it applies to the in vitro assay of the enzyme γ-glutamyl hydrolase (GGH, EC 3.4.22.12). Distinct separation of MTX and polyglutamylated forms (up to glu₄) is achieved within 10 min using a 75 μm I.D. capillary (50 cm, +25 kV), and enables quantitation of both reactant and enzyme products. As activity can be reliably determined using less than 5×10⁵ eukaryotic cells, this new technique can be used to measure GGH in patient tumor samples and investigate the relationship between GGH levels and clinical MTX resistance.     

Antimicrobial peptides (AMPs): A promising class of antimicrobial compounds

Antimicrobial peptides (AMPs) are compounds, which have inhibitory activity against microorganisms. In the last decades, AMPs have become powerful alternative agents that have met the need for novel anti-infectives to overcome increasing antibiotic resistance problems. Moreover, recent epidemics and pandemics are increasing the popularity of AMPs, due to the urgent necessity for effective antimicrobial agents in combating the new emergence of microbial diseases. AMPs inhibit a wide range of microorganisms through diverse and special mechanisms by targeting mainly cell membranes or specific intracellular components. In addition to extraction from natural sources, AMPs are produced in various hosts using recombinant methods. More recently, the synthetic analogues of AMPs, designed with some modifications, are predicted to overcome the limitations of stability, toxicity and activity associated with natural AMPs. AMPs have potential applications as antimicrobial agents in food, agriculture, environment, animal husbandry and pharmaceutical industries. In this review, we have provided an overview of the structure, classification and mechanism of action of AMPs, as well as discussed opportunities for their current and potential applications.     

Dual function of the Drosophila Alk1/Alk2 ortholog Saxophone shapes the Bmp activity gradient in the wing imaginal disc

Wing patterning in Drosophila requires a Bmp activity gradient created by two Bmp ligands, Gbb and Dpp, and two Bmp type I receptors, Sax and Tkv. Gbb provides long-range signaling, while Dpp signals preferentially to cells near its source along the anteroposterior (AP) boundary of the wing disc. How each receptor contributes to the signaling activity of each ligand is not well understood. Here, we show that while Tkv mediates signals from both Dpp and Gbb, Sax exhibits a novel function for a Bmp type I receptor: the ability to both promote and antagonize signaling. Given its high affinity for Gbb, this dual function of Sax impacts the function of Gbb in the Bmp activity gradient more profoundly than does Dpp. We propose that this dual function of Sax is dependent on its receptor partner. When complexed with Tkv, Sax facilitates Bmp signaling, but when alone, Sax fails to signal effectively and sequesters Gbb. Overall, our model proposes that the balance between antagonizing and promoting Bmp signaling varies across the wing pouch, modulating the level and effective range, and, thus, shaping the Bmp activity gradient. This previously unknown mechanism for modulating ligand availability and range raises important questions regarding the function of vertebrate Sax orthologs.