Description of Alaeuris stehlini n. sp. and Alaeuris numidica canariensis n. ssp. (Nematoda, Pharyngodonidae), parasite of Gallotia stehlini, lacertid of Grand Canary Island (Spain)

Pharyngodonid nematodes (Oxyuroidea) belonging to the genus Alaeuris Thapar, 1925, were collected from the posterior gut of Gallotia stehlini (Lacertidae) from Grand Canary Island. Two species Alaeuris stehlini n. sp. and Alaeuris numidica canariensis n. ssp. were identified. The new species is described in which the long thin males are characterized by narrow caudal alae, a rounded first pair of adanal papillae non pedunculate, the second pair attached and elongate, the three pair teated; a short narrow V plate and a relatively long caudal appendage. The females are also long and thin with a slightly salient vulva, a conical pointed caudal appendage, oesophageal length approximately one third of body, excretory pore below the oesophageal bulb. The new subspecies most closely resembles Alaeuris numidica numidica. (Seurat, 1918) Petter, 1966 and Alaeuris numidica madagascariensis Petter, 1966.     

PETAL LOSS gene regulates initiation and orientation of second whorl organs in the Arabidopsis flower

PETAL LOSS is a new class of flower development gene whose mutant phenotype is confined mostly to the second whorl. Two properties are disrupted, organ initiation and organ orientation. Initiation is frequently blocked, especially in later-formed flowers, or variably delayed. The few petals that arise occupy a wider zone of the flower primordium than normal. Also, a minority of petals are trumpet-shaped, thread-like or stamenoid. Studies of ptl combined with homeotic mutants have revealed that the mutant effect is specific to the second whorl, not to organs with a petal identity. We propose that the PTL gene normally promotes the induction of organ primordia in specific regions of the second floral whorl. In ptl mutants, these regions are enlarged and organ induction is variably reduced, often falling below a threshold. A dominant genetic modifier of the ptl mutant phenotype was found in the Landsberg erecta strain that significantly boosts the mean number of petals per flower, perhaps by reinforcing induction so that the threshold is now more often reached. The second major disruption in ptl mutants relates to the orientation adopted by second whorl organs from early in their development. In single mutants the full range of orientations is seen, but when B function (controlling organ identity) is also removed, most second whorl organs now face outwards rather than inwards. Orientation is unaffected in B function single mutants. Thus petals apparently perceive their orientation within the flower primordium by a mechanism requiring PTL function supported redundantly by that of B class genes.     

Reduced insulin secretion in response to nutrients in islets from malnourished young rats is associated with a diminished calcium uptake

Changes in (45)Ca uptake and insulin secretion in response to glucose, leucine, and arginine were measured in isolated islets derived from 4-week-old rats born of mothers maintained with normal protein (NP, 17%) or low protein (LP, 6%) diet during pregnancy and lactation. Glucose provoked a dose-dependent stimulation of insulin secretion in both groups of islets, with basal (2.8 mmol/L glucose) and maximal release (27.7 mmol/L glucose) significantly reduced in LP compared with NP islets. In the LP group the concentration-response curve to glucose was shifted to the right compared with the NP group, with the half-maximal response occurring at 16.9 and 13.3 mmol/L glucose, respectively. In LP islets, glucose-induced first and second phases of insulin secretions were drastically reduced. In addition, insulin response to individual amino acids, or in association with glucose, was also significantly reduced in the LP group compared with NP islets. Finally, in LP islets the (45)Ca uptake after 5 minutes or 90 minutes of incubation (which reflect mainly the entry and retention, respectively, of Ca(2+)), was lower than in NP islets. These data indicate that in malnourished rats both initial and sustained phases of insulin secretion in response to glucose were reduced. This poor secretory response to nutrients seems to be the consequence of an altered Ca(2+) handling by malnourished islet cells.     

The 2.15 A crystal structure of CG-16, the developmentally regulated homodimeric chicken galectin

Differential developmental regulation of expression, fine-specificity differences in ligand recognition and disparate capacity for homodimerization are characteristics of the two currently known proto-type chicken galectins. The X-ray crystal structure of the first avian galectin, the homodimeric agglutinin from chicken liver (CG-16), has been solved in the absence of ligand in two crystal forms. Although the arrangement of lectin dimers in the two crystals is different, the structure of the monomers and their association into the extended beta-sandwich that characterises the dimer are virtually identical. The fold establishes a beta-sandwich motif composed of a five-stranded and a six-stranded beta-sheet evocative of proto-type mammalian galectins. The carbohydrate-binding site is occupied by six water molecules that take the place of the sugar in the complex. They help to stabilise in the absence of the ligand the spatial arrangement of the amino acid side-chains involved in sugar recognition. Docking of N-acetyllactosamine into the binding site reveals that three of these water molecules, which are in direct contact with the protein, occupy positions equivalent to the key sugar hydroxyl groups, namely the hydroxyls at positions 4 and 6 of the galactose unit and at position 3 of the N-acetylglucosamine unit. Crystallographic data are fully consistent with the binding features in solution previously derived from chemical mapping with deoxy, fluoro and O-methyl derivatives and laser photo-CIDNP (chemically induced dynamic nuclear polarisation) studies. The possible molecular basis for the monomeric character of the chicken intestinal galectin as well as potential mechanisms of oxidative inactivation by disulphide bridging are evaluated on the basis of the given structural information concerning the CG-16 dimer interface and the cysteine residues, respectively.     

The effect of chloroquine on the production of interferon-gamma, interleukin (IL)-4, IL-6, and IL-10 in Plasmodium chabaudi chabaudi in infected C57BL6 mice

The effect of chloroquine (CQ) on the production pattern of interferon (IFN)-gamma, interleukin (IL)-4, IL-6, and IL-10 in female C57BL6 mice infected with Plasmodium chabaudi chabaudi AS was evaluated during a period of 35 days. Our data confirm that there is a switch from a T helper cell (Th)1 to a Th2 response during malaria infection in this model. Proliferation assays showed a decreased stimulation index in infected mice that was further reduced in infected mice treated with CQ. Noninfected control mice treated with CQ showed an increase production of IFN-gamma. However, no detectable changes in IL-4, IL-6, and IL-10 production were observed in this group. CQ treatment of infected mice resulted in parasite clearance that was associated with an earlier production of IL-4, IL-6, and IL-10 when compared with nontreated infected mice. We suggest that this earlier switch to a Th2 response is a consequence of parasite killing rather than CQ interference with cytokine production.     

Identification of the gland secreting oviposition-deterring pheromone in the cabbage seed weevil,Ceutorhynchus assimilis,and the mechanism of pheromone deposition

After laying an egg into a pod of Brassica napus, the female cabbage seed weevil, Ceutorhynchus assimilis, brushes the caudal setae of the eighth abdominal tergite (VIII UT) on the host pod as she walks along it, depositing oviposition-deterring pheromone (ODP). The VIII UT is periodically extended and withdrawn, thus repeatedly rubbing against the posterior fold of the seventh urotergite (VII UT) which bears the individual outlets of glandular epidermal cells. In post-diapause, sexually mature, gravid (i.e. oviferous) females (virgin or mated) the cells of this VII UT gland were hypertrophic, showing intense secretory activity. Extracts of VII UT from these individuals elicited strong electrophysiological responses from antennal club gustatory sensilla and deterred oviposition. In pre-diapause (sexually immature) females, the cells of the VII UT gland were neither hypertrophic nor active and an extract of their VII UT elicited no significant electrophysiological or behavioural response. Extract of female rectum was a less potent oviposition deterrent than VII UT extract and elicited an electrophysiological response similar to male rectum extract. An extract of ovarian calyces and ovaries elicited no behavioural response. We conclude that ODP is secreted by the epidermal cells of the VII UT posterior fold.     

Melatonin activates Th1 lymphocytes by increasing IL-12 production

Melatonin could act on immune system by regulating cytokine production of immunocompetent cells. The hormone enhances IL-2, IFN-gamma and IL-6 production by cultured human mononuclear cells. As enhancement of IL-6 production is related to monocyte activation by melatonin, the hormone acts on human lymphoid cells causing a Th1-type response. This paper shows that melatonin seems to promote a Th1-response by increasing IL-12 production. The hormone enhances IL-12 production by cultured monocytes under suboptimal stimulation in a dose-dependent way. The effect of the hormone increases when PBMCs are incubated with melatonin before monocyte isolation. Enhanced IL-12 production by melatonin can also be shown in cultured human mononuclear cells.     

The w/w+ SMART assay of Drosophila melanogaster detects the genotoxic effects of reactive oxygen species inducing compounds

The somatic mutation and recombination w/w+ eye assay has been used for genotoxic evaluation of a broad number of chemicals with different action mechanisms yielding high values of sensitivity, specificity and accuracy. The aim of this work was to determine the utility of this assay in the evaluation of reactive oxygen species inducers. For this, we have tested eight compounds: diquat, paraquat, menadione, juglone, plumbagin, streptonigrin, tert-butyl hydroperoxide and 4-nitroquinoline 1-oxide, using the Drosophila Oregon K strain which had previously shown advantageous conditions to test this type of compounds. Diquat was the only chemical for which the results were clearly negative, probably because its high toxicity, whereas indications of a marginal genotoxicity raised for menadione. The remaining compounds were evaluated as positives. The conclusion of these experiments is that the w/w+ assay is capable to detect genotoxic effects induced by compounds that generate reactive oxygen species through different action mechanisms.