A Xenopus c-kit-related receptor tyrosine kinase expressed in migrating stem cells of the lateral line system

The mammalian c-kit receptor tyrosine kinase gene is required during embryogenesis for the survival and/or proliferation of three migrating stem cell populations: primordial germ cells, haematopoietic stem cells and neural crest-derived melanoblasts. We have cloned a Xenopus gene, XKrkl, whose closest relative is c-kit. Differences in the expression pattern suggest that XKrkl is not the Xenopus homologue of c-kit; however, it is expressed in a migrating stem cell population, the precursor cells for the mechanosensory lateral line system. XKrkl is the first reported marker for lateral line stem cells.     

The history of the cattle tick Boophilus microptus in Australia and achievements in its control

For more than 100 years, tick fever and the cattle tick have caused tremendous financial loss to cattle producers around the world. Since Australia became infected with the disease and infested with its tick vector in the mid-19th century, a great deal of research effort has been directed towards their effective control by Australian farmers, administrators and scientists. Such research has yielded information which has facilitated the development of various control strategies that have equal application in other countries afficted with the same problem. It has been demonstrated that integration of a variety of these strategies is necessary for long-lasting control.     

Structural analysis of DNA-PKcs: modelling of the repeat units and insights into the detailed molecular architecture

DNA-dependent protein kinase (DNA-PK) is part of the eukaryotic DNA double strand break repair pathway and as such is crucial for maintenance of genomic stability, as well as for V(D)J (variable-diversity-joining) recombination. The catalytic subunit of DNA-PK (DNA-PKcs) belongs to the phosphatidylinositol-3 (PI-3) kinase-like kinase (PIKK) superfamily and is comprised of approximately 4100 amino acids. We have used a novel repeat detection method to analyse this enormous protein and have identified two different types of helical repeat motifs in the N-terminal region of the sequence, as well as other previously unreported features in this repeat region. A comparison with the ATMs, ATRs, and TORs show that the features identified are likely to be conserved throughout the PIKK superfamily. Homology modelling of parts of the DNA-PKcs sequence has been undertaken and we have been able to fit the models to previously obtained electron microscopy data. This work provides an insight into the overall architecture of the DNA-PKcs protein and identifies regions of interest for further experimental studies.     

First record of the opal chimaera,Chimaera opalescens (Holocephali: Chimaeridae) and revision of the occurrence of the rabbitfish Chimaera monstrosa in the Azores waters

The presence of the opal chimaera, Chimaera opalescens, is reported for the first time in the deep waters of the Azores, with the capture of four specimens by fishermen and the video recording of an additional five individuals. Species identification was supported by the 646 bp sequenced fragment of the mitochondrial gene cytochrome oxidase subunit I. Because C. opalescens is a recently recognised species that had been recurrently misidentified as rabbitfish, Chimaera monstrosa, the historical data of C. monstrosa in the Azores were reviewed to assess the possible presence of both Chimaera species in the region. Although several authors have reported the occurrence of C. monstrosa in the Azorean waters since the 1800s, the majority of these are based on only three specimens caught during the late 1800s. The investigation performed using literature and examination of the museum specimens still available concluded that the most likely scenario is that C. monstrosa is absent from the Azores and past records of that species in the region are most likely misidentifications of C. opalescens.     

The evolution of the amphibian lateral line system and its bearing on amphibian phylogeny

In modern amphibians that are aquatic the lateral line system is organized, by order, as follows: caecilians have electroreceptive ampullary organs and single rows of mechanoreceptive neuromast organs; generalized anurans have single rows of neuromasts that divide in a transverse plane to form secondary neuromasts or stitches, they do not have ampullary organs; generalized urodeles have ampullary organs, transverse stitches, and double or triple rows of neuromasts. Fossil evidence indicates that early amphibians had both ampullary organs and single rows of neuromasts embedded in bone. With time, receptors became epidermal in all three orders. Modern caecilians have retained the primitive receptor arrangement. I propose that the common ancestor of anurans and urodeles had transverse stitches, and that this character allies these two groups. Subsequent to the anuranurodele split, anurans lost their ampullary organs, perhaps concomitant with developing specializations for herbivory. Urodeles developed orthogonal neuromast couplets und triplets. In modern anurans und urodeles, transverse stitches are correlated with pond dwelling, while ampullary organs are correlated with carnivory, suggesting that the anuran-urodele ancestor(s) was a (were) pond-dwelling carnivore(s).     

Persistent activity in limbic system neurons: neurophysiological and modeling perspectives

Neural activity persisting for one to hundreds of seconds has been postulated to be a substrate of memory. This review article illustrates examples of such activity in limbic system structures including the hippocampus, postsubiculum, and the anterodorsal thalamus. These neuronal responses include better known correlates with the spatial position as well as with head direction of the animal relative to its environment as well as other lesser known examples. Since head direction responses are greater when the animal is actively moving than when passively rotated, it has been proposed that there might be a general mechanism where the behavioral state of the animal can provide modulatory gating of such persistent signals. This would regulate the relative influence of these signals on downstream structures. Neural network attractor models of the head direction cell system are presented to demonstrate how these responses might originate, as well as the dynamics by which they are updated during movements.     

Basiepidermal nervous system in Nemertoderma westbladi (Nemertodermatida): GYIRFamide immunoreactivity

The Nemertodermatida are a small group of microscopic marine worms. Recent molecular studies have demonstrated that they are likely to be the earliest extant bilaterian animals. What was the nervous system (NS) of a bilaterian ancestor like? In order to answer that question, the NS of Nemertoderma westbladi was investigated by means of indirect immunofluorescence technique and confocal scanning laser microscopy. The antibodies to a flatworm neuropeptide GYIRFamide were used in combination with anti-serotonin antibodies and phalloidin-TRITC staining. The immunostaining revealed an entirely basiepidermal NS. A ring lying outside the body wall musculature at the level of the statocyst forms the only centralisation, the "brain". No stomatogastric NS has been observed. The GYIRFamide immunoreactive part of the "brain" is formed of loosely packed nerve fibres with multiple small neurones and a few large ones. The peptidergic and aminergic patterns of the NS do not correspond to each other: the former is more developed on the ventral side, the latter is more pronounced on the dorsal side. A pair of GYIRFamide immunoreactive nerve cords innervates the ventral side of the animal, the mouth and the male genital opening. The nemertodermatids studied to-date display no common NS pattern. Possible synapomorphies of the Acoelomorpha are discussed. The study demonstrates that the nemertodermatid NS possesses a number of plesiomorphic features and appears more primitive than the NS in other worms, except the Xenoturbellida. The bilaterian ancestor supposedly possessed only a basiepidermal nerve net and had no centralised brain-like structures and no stomatogastric NS.     

Itraconazole and leishmaniasis: A randomised double-blind trial in cutaneous disease

Cutaneous leishmaniasis (CL) is a vector-borne parasitic disease of the skin. Previous open controlled studies with oral itraconazole suggest that it was effective for CL in India. Twenty patients with localised CL participated in this trial. Patients were allocated randomly to receive capsule itraconazole and matching placebo for 6 weeks. No topical medicines were used. Demonstration of Leishmania by slit smear was mandatory. Prior to, periodically during and 3 months after completion of therapy an overall clinical assessment, liver function tests and urinalysis were performed. On decoding, out of the 10 cases receiving drug itraconazole, 7 were declared cured by clinical and parasitological criteria. No major side-effects were noted. Spontaneous remission was observed in 1 case in the placebo group at 3 months follow up. Oral itraconazole has a promising antileishmanial potential and may thus secure CL patient from the hazards of antimonials.     

Feeding ecology and trophic level of Chimaera monstrosa Linnaeus, 1758 (Holocephali: Chimaeridae) in the Eastern Mediterranean

The feeding ecology of Chimaera monstrosa at a depth of 550?m was studied off S??ac?k Bay, Eastern Mediterranean, in 2008. Forty males and 57 females with a length between 7.80 and 45.5?cm were caught. 33 stomachs contained food items. The diet was composed of 11 prey items belonging to 6 groups: Bryozoa, Cnidaria, Crustacea, Mollusca, Tunicata, and Teleostei, of which Crustacea (IRI% [Index of Relative Importance]=80) and Mollusca (IR%=16) were the most abundant prey groups. The trophic level was estimated at 3.50, which is similar to the results from other studies in the western and northern part of the Mediterranean and the Atlantic Ocean but is higher than in the North Sea.     

Homeostatic plasticity in the CNS: synaptic and intrinsic forms

The study of experience-dependent plasticity has been dominated by questions of how Hebbian plasticity mechanisms act during learning and development. This is unsurprising as Hebbian plasticity constitutes the most fully developed and influential model of how information is stored in neural circuits and how neural circuitry can develop without extensive genetic instructions. Yet Hebbian plasticity may not be sufficient for understanding either learning or development: the dramatic changes in synapse number and strength that can be produced by this kind of plasticity tend to threaten the stability of neural circuits. Recent work has suggested that, in addition to Hebbian plasticity, homeostatic regulatory mechanisms are active in a variety of preparations. These mechanisms alter both the synaptic connections between neurons and the intrinsic electrical properties of individual neurons, in such a way as to maintain some constancy in neuronal properties despite the changes wrought by Hebbian mechanisms. Here we review the evidence for homeostatic plasticity in the central nervous system, with special emphasis on results from cortical preparations.     

Tectal responses to potassium loads and subsequent visual stimuli in the toad, Bufo bufo

Calling male toads were tested behaviourally for their prey catching responses to wormlike stimuli and assigned to groups of non-hungry and hungry depending on their prey catching motivation before being prepared for visual unit, massed unit and slow potential shift (SPS) recording from the optic tectum. Control recordings to visual stimuli were made before recording the effects of application of isotonic solutions containing concentrations of 0-41 mM K(+). Application of solution was followed by presentation of the visual stimulus while the solution still bathed the tectum. The best tectal responses were made to large square visual stimuli in the non-hungry toads, perhaps because recordings were made in the breeding season. Responses of the tectum to solution addition were significant in the concentration range of 7-17 mM K(+). Hungry toads showed an earlier, smaller response than non-hungry (sexually motivated) animals. When the visual stimulus was presented, there were unit and massed unit responses at all bathing solution concentrations, which were larger in non-hungry animals. These experiments revealed that toads motivated to feed respond earlier than non-hungry toads to application of artificial CSF to the tectum, though non-hungry toads responded best to the subsequent visual stimulus.     

Conditioned medium from osteocytes stimulates the proliferation of bone marrow mesenchymal stem cells and their differentiation into osteoblasts

Osteocytes are the most abundant cells in bone and there is increasing evidence that they control bone remodeling via direct cell-to-cell contacts and by soluble factors. In the present study, we have used the MLO-Y4 cell line to study the effect of osteocytes on the proliferation, differentiation and bone-forming capacity of bone marrow mesenchymal stem cells (MSC). Conditioned media (CM) from osteocytic MLO-Y4 and osteoblastic MC3T3-E1 cell lines were collected and added on mouse bone marrow cultures, in which MSC were induced to osteoblasts. There was a significant increase in alkaline phosphatase activity and osteocalcin expression in the presence of MLO-Y4 CM. No such stimulus could be observed with MC3T3-E1 CM. There was almost 4-fold increase in bone formation and up to 2-fold increase in the proliferation of MSC with MLO-Y4 CM. The highly proliferating bone marrow cells were negative for ALP and OCN, suggesting that they could represent early osteoblast precursors. MLO-Y4 CM did not enhance the viability of mature osteoblasts nor protected them of apoptosis. This is the first study to describe soluble signals between osteocytes and osteoblasts and there most likely are several still unidentified or unknown factors in osteocyte CM. We conclude that osteocytes have an active stimulatory role in controlling bone formation.     

The role of polyunsaturated fatty acids in the expression of torpor by mammals: a review

Heterothermic mammals increase the proportion of polyunsaturated fatty acids (PUFA) in their body fats prior to entering torpor. Because PUFA have low melting points, it is thought that they play an important role in maintaining the fluidity of depot fats and membrane phospholipids at low body temperatures. However, PUFA are more prone to autoxidation when exposed to reactive oxygen species (ROS) during torpor and during the periodic arousals that characterize hibernation. A lack of PUFA or an excess of PUFA may constrain the use of torpor by heterothermic mammals. We performed a mixed model meta-analysis of 17 controlled-feeding studies to test the effect of dietary PUFA on the depth and expression of torpor by daily heterotherms and hibernators. We also reviewed the literature on the PUFA content of the diet and depot fats of heterothermic mammals to address two principal topics: (1) Do low dietary levels of PUFA reduce the expression of torpor under laboratory conditions and, if so, are free-ranging animals constrained by a lack of PUFA? (2) Do high dietary levels of PUFA result in a reduction in the use, depth, and duration of torpor and, if so, do free-ranging animals seek to optimize rather than maximize PUFA intake? Low-PUFA diets consistently increase the lower setpoint for body temperature and minimum metabolic rate for both hibernators and daily heterotherms. Above the lower setpoint, low-PUFA diets usually increase body temperature and metabolic rate and decrease the duration of torpor bouts and this effect is similar for hibernators and daily heterotherms. Free-ranging rodent hibernators have dietary PUFA intakes that are far higher than those of the low-PUFA diets offered in controlled-feeding experiments, so these hibernators may never experience the constraints associated with a lack of PUFA. Diets of free-ranging insectivorous bats and echidnas have PUFA levels that are less than half as high as those offered in experimental low-PUFA diets, yet they exhibit deep and extended bouts of torpor. We argue that alternate mechanisms exist for maintaining the fluidity of body fats and that high-PUFA intake may not be a prerequisite for deep and extended bouts of torpor. Four studies indicate that animals that were fed high-PUFA diets are reluctant to enter torpor and show shallower and shorter torpor bouts. Although authors attribute this response to autoxidation, these animals did not have a higher PUFA content in their depot fats than animals where PUFA was shown to enhance torpor. We suggest that these contradictory results indicate inter-specific or inter-individual variation in the ability to control ROS and limit autoxidation of PUFA. High dietary levels of PUFA will constrain the expression of torpor only when the oxidative challenge exceeds the capacity of the antioxidant defence system. Studies of diet selection indicate that insectivorous species with low dietary PUFA levels seek to maximize PUFA intake. However, herbivorous species that have access to plants and plant parts of high-PUFA content do not appear to maximize PUFA intake. These data suggest that animals attempt to optimize rather than maximize PUFA intake. The effect of PUFA should be viewed in the light of a cost-benefit trade-off, where the benefit of high-PUFA intake is an easier access to low body temperatures and the cost is increased risk of autoxidation.     

Ewe effect: endocrine and testicular changes in experienced adult and inexperienced young Corriedale rams used for the ram effect

Changes in LH, FSH, and testosterone concentrations, testicular firmness and resilience, and scrotal circumference were monitored in 16 Corriedale rams (8 experienced adult and 8 inexperienced young) for 20 days during which they were used to stimulate ewes. The experiment was conducted during November (mid-non-breeding season). Increases (P<0.05) were observed in LH and testosterone concentrations and in testicular firmness and resilience during the first 4 days when rams were in permanent contact with estrual ewes. During the following 13 days, when rams were in contact with non-estrual ewes (i.e. initially estrual ewes were no longer in estrus), LH and testosterone concentrations decreased. When initially anestrous ewes exhibited estrus 17 to 20 days later, concentrations of testosterone increased. Testicular firmness and resilience remained high throughout the period. We conclude that: (1) rams used to stimulate anestrous ewes show an increase in LH and testosterone concentrations beginning at 12 h after joining, and greater concentrations are maintained while estrual ewes and mating are allowed; and (2) estrous and mating activity are probably the most important stimuli for the increase in hormone concentrations.     

Gene expression in the elicitation phase of guinea pig DTH and CHS reactions

Delayed-type hypersensitivity (DTH) reactions are divided into classical DTH induced by protein antigens and contact hypersensitivity (CHS) induced by haptens. It has been reported that different cytokines and T cell subsets are involved in the induction of each DTH reaction. We previously isolated many genes whose expression is elevated during elicitation of skin DTH reaction in guinea pigs. In this study, we focused on the expression of tryptophanyl-tRNA synthetase (WRS), ferritin heavy chain and major histocompatibility complex (MHC) class II genes to investigate the different regulatory mechanisms in classical DTH and CHS. Furthermore, the expression of various cytokines and chemokines was examined. WRS expression in classical DTH was higher than that in CHS, and the expression of interferon-gamma but not that of transforming growth factor-beta showed similar patterns. MHC class II mRNA increased only in classical DTH. The differential expression of WRS and MHC class II genes in classical DTH might be caused by the differential expression of interferon-gamma and/or the involvement of CD4(+) T cells in classical DTH, respectively. In contrast, the expression of ferritin heavy chain and interleukin-1beta was elevated in CHS, and also by treatment with dinitrochlorobenzene in unsensitized guinea pigs, and expression of both was correlated.     

The influence of task and angle on torque production and muscle activity at the elbow

This study investigated the effect of changing internal mechanical variables and task demands on muscle activity and torque production during high effort isometric contractions of the elbow flexors. The effect of adding a 50% maximal voluntary contraction (MVC) of supination to an MVC of elbow flexion was studied over a range of angles from 30° to 110° of elbow flexion. Surface EMGs were recorded from the biceps brachii (BIC), brachioradialis (BRAD) and triceps brachii (TRI) of 10 healthy subjects. BIC was the only muscle to show a consistent trend of increasing root mean square (rms) EMG with increasing elbow flexion angle. BIC activity also remained constant or increased with the addition of the supination task at all angles. In contrast, BRAD showed decreased activity when supination was added at several angular positions. Maximal flexion torque was reduced when the second task of submaximal supination was added. This torque reduction was statistically significant at all angles except 70° and appeared related to the decreased contribution from BRAD. In a small subset of subjects, however, BRAD activity did not decrease when the second degrees of freedom (df) task was added. These subjects exhibited higher flexion torques averaged over task than the majority, at all angles except 30°. These data support the view that internal mechanical considerations influence the manner in which the central nervous system (CNS) distributes activity to muscular synergists in response to altered task demands. Further, subject-specific patterns exist which must be recognized if these findings are to be incorporated in training or rehabilitation programmes.     

The kinetic disposition of pyrantel citrate and pamoate and their efficacy against pyrantel-resistant Oesophagostomum dentatum in pigs

The pharmacokinetic disposition of pyrantel after intravenous (i.v.) and oral (p.o.) administration as the citrate and p.o. administration as the pamoate salt was determined in pigs. Following i.v. administration pyrantel was quickly cleared from the bloodstream, exhibiting a terminal halflife of 1.75 ± 0.19h and a residence time (MRT) of 2.54 ± 0.27h. After p.o. administration as the citrate salt, the absorption time (MAT) of pyrantel was 2.38 ± 0.25h and although significant quantities of pyrantel were absorbed (mean bioavailability of 41%) the rapid clearance resulted in a MRT of only 4.92 ± 0.36h. By comparison, the significantly extended MAT of the less soluble pamoate salt resulted in reduced circulating concentrations and a significantly lower mean bioavailability of 16%. The poor efficacy of pyrantel citrate against nematodes inhabiting the large intestine of pigs is therefore suggested to result from insufficient quantities of drug passaging to the site of infection. When tested against pyrantel-resistant adult Oesophagostomum dentatum the efficacy of pyrantel citrate was only 23%, whereas the efficacy of the lesser absorbed pyrantel pamoate was 75%. These results indicate that for maximum activity pyrantel should be administered to pigs as the pamoate salt.     

Infant feeding practices and chronic child malnutrition in the Indian states of Karnataka and Uttar Pradesh

As measured by degree of stunting, close to half of India's children suffer from chronic malnutrition and about a quarter from severe chronic malnutrition. Data from the 1998-1999 National Family Health Survey (NFHS) are analysed to assess whether recommended infant feeding practices help to alleviate the prevalence of stunting. The evidence supports some recommended practices, including the advice that mother not squeeze the colostrum from her breasts, not use a feeding bottle with a nipple, exclusive breastfeeding for the first 4-6 months and feeding supplementary foods (solids and mushy foods) at about 7 months, and suggests that, for some children, better feeding practices could reduce the prevalence of severe stunting by up to 30%. The paper also examines a range of other issues related to stunting--whether medical supplementations and inoculations have an effect, whether mothers more actively involved in health decisions have less stunted children, and the links between stunting, diarrhoea and anaemia. An explanation is offered for the positive relationship between using oral rehydration salts and stunting.