Halacaridae (Acari) from Pujada Bay (the Philippines): description and biogeography of three new and two known species

Three new and two known Halacaridae species belonging to the genus Copidognathus collected among seagrass plants in Pujada Bay (Mindanao, the Philippines) are described. Copidognathus ivanomorsellii sp.n. belongs to the `Copidognathus gibbus' group and shows the main characteristics of the group but differs from known species as the two triangular porose areolae on AD are joined together, the typical shape of the lateral line of the costae of PD, the distance between the anterior gland pore on PD and the lateral margin of PD, tarsi III and IV with 4:4 dorsal setae, ventral seta on trochanter III almost as long as ventral seta of basifemur III, anterior end of AD with rosette pores, AE and GA only laterally fused but separated in the middle portion and elongated frontal spine (projection) on AD, lateral claws with very fine pecten ventrally. A zoogeographical distribution of the `C. gibbus' group is reported. Copidognathus pujadus sp.n. belongs to the `Copidognathus bairdi' group and is loosely related to C. sideus Bartsch, 1982, C. sidellus Bartsch, 1985 and C. euryalus Bartsch, 1997b. Differences were observed and are discussed. Copidognathus philippinensis sp.n. belongs to the `Copidognathus curassaviensis' group but differs from the four known species within the group by the elevated ridge below the middle two areolae on AD area which connects the two areolae. In addition, two known species i.e. Copidognathus uniscutatus Bartsch, 1984, C. faubeli Bartsch, 1986 were collected. The Halacaridae fauna recorded so far from the Philippines is summarised and discussed.     

Effect of food preservation on the grazing behavior and on the gut flora of the harpacticoid copepod Paramphiascella fulvofasciata

Harpacticoids owe their ‘reputation’ as primary consumers in aquatic food webs to their substantial grazing on diatoms, thus assuring an efficient energy flow to higher trophic levels. Due to the complex feeding behavior of harpacticoids, the nature and dynamics of diatom-harpacticoid trophic interactions remain poorly understood. In addition, there is a growing interest from aquaculture industry in mass-culturing harpacticoids with algal foods but the labor costs of maintaining algal stock cultures are high. This study focuses on the palatability of preserved diatoms for copepods and considers the possible role of bacterially mediated effects on diatom food uptake.The grazing of Paramphiascella fulvofasciata on a preserved freeze-dried diatom diet was tested and compared to the grazing on fresh cells. P. fulvofasciata assimilated the preserved diet, but assimilation of fresh cells was higher. When both cell types were mixed, no selective feeding was observed. Community fingerprinting of the bacteria associated with diatoms and fecal pellets suggests that the copepod gut flora was modified depending on the food source. Furthermore, the results suggest that the egestion of gut bacteria enriches the microenvironment and this can have an additional influence on the feeding behavior of the copepod.Experimental research using preserved foods must take into account that copepod grazing assimilations of fresh foods are likely to be significantly higher. Yet, the stated high assimilation of the mixed diet, encourages further exploration of the application of preserved ‘balanced’ foods for harpacticoid mass-culturing.     

Dectin-1 interaction with tetraspanin CD37 inhibits IL-6 production

C-type lectins are pattern-recognition receptors important for pathogen binding and uptake by APCs. Evidence is accumulating that integration of incoming cellular signals in APCs is regulated by grouping of receptors and signaling molecules into organized membrane complexes, such as lipid rafts and tetraspanin microdomains. In this study, we demonstrate that C-type lectin dectin-1 functionally interacts with leukocyte-specific tetraspanin CD37. Dectin-1 and CD37 colocalize on the surface of human APCs. Importantly, macrophages of CD37-deficient (CD37(-/-)) mice express decreased dectin-1 membrane levels, due to increased dectin-1 internalization. Furthermore, transfection of CD37 into a macrophage cell line elevated endogenous dectin-1 surface expression. Although CD37 deficiency does not affect dectin-1-mediated phagocytosis, we observed a striking 10-fold increase of dectin-1-induced IL-6 production in CD37(-/-) macrophages compared with wild-type cells, despite reduced dectin-1 cell surface expression. Importantly, the observed increase in IL-6 production was specific for dectin-1, because signaling via other pattern-recognition receptors was unaffected in CD37(-/-) macrophages and because the dectin-1 ligand curdlan was used. Taken together, these findings show that tetraspanin CD37 is important for dectin-1 stabilization in APC membranes and controls dectin-1-mediated IL-6 production.     

Ca-induced fusion of cardiolipin/phosphatidylcholine vesicles monitored by mixing of aqueous contents

The kinetics of Ca²⁺-induced fusion of large (0.1 μm) unilamellar cardiolipin/phosphatidylcholine (1:1) vesicles have been investigated by continuous monitoring of the mixing of the aqueous vesicle contents. In parallel, release of vesicle contents to the external medium has been followed. Initial fusion of the vesicles is non-leaky, release of vesicle contents being largely a secondary phenomenon. The minimal Ca²⁺ concentration required for fusion in this system is approx. 9 mM. At higher Ca²⁺ concentrations fusion is extremely fast, occurring on the time scale of seconds.     

Yeasts and fungi occurring in ensiled whole-crop maize and other ensiled vegetable crops

The yeast flora of whole-crop maize ensiled for two weeks was predominated by Candida holmii, C. lambica, C. milleri, Hansenula anomala and Saccharomyces dairensis. Inoculation with other yeast species reported in the literature to prevail in maize or wheat silages did not alter the yeast flora. At 25 or 30° C the ascomycetous fermentative species found at 20° C were accompanied with ascomycetous non-fermentative fungi, i.c. Exophiala jeanselmei and Verticillium psalliotae, by the non-fermentative imperfect basidiomycetous yeast Rhodotorula mucilaginosa and by the weakly fermentative imperfect ascomycetous yeast Trichosporon adeninovorans.The yeast flora of other vegetable crops, ensiled at 20° C for two weeks, was predominated by the same species that prevailed in ensiled maize, provided the crop did not contain mustard oils or menthol. If these compounds occurred in the crops, the yeast flora was predominated by nonfermentative species like Candida famata, Stephanoascus ciferrii, Rhodotorula minuta, Rh. rubra and Trichosporon cutaneum.     

Obstruction of polyubiquitination affects PTS1 peroxisomal matrix protein import

Pex4p is an ubiquitin-conjugating enzyme that functions at a late stage of peroxisomal matrix protein import. Here we show that in the methylotrophic yeast Hansenula polymorpha production of a mutant form of ubiquitin (Ub(K48R)) has a dramatic effect on PTS1 matrix protein import. This effect was not observed in cells lacking Pex4p, in which the peroxisome biogenesis defect was largely suppressed. These findings provide the first indication that the function of Pex4p in matrix protein import involves polyubiquitination. We also demonstrate that the production of Ub(K48R) in H. polymorpha results in enhanced Pex5p degradation. A similar observation was made in cells in which the PEX4 gene was deleted. We demonstrate that in both strains Pex5p degradation was due to ubiquitination and subsequent degradation by the proteasome. This process appeared to be dependent on a conserved lysine residue in the N-terminus of Pex5p (Lys21) and was prevented in a Pex5p(K21R) mutant. We speculate that the degradation of Pex5p by the proteasome is important to remove receptor molecules that are stuck at a late stage of the Pex5p-mediated protein import pathway.     

Linkage and association studies identify a novel locus for Alzheimer disease at 7q36 in a Dutch population-based sample

We obtained conclusive linkage of Alzheimer disease (AD) with a candidate region of 19.7 cM at 7q36 in an extended multiplex family, family 1270, ascertained in a population-based study of early-onset AD in the northern Netherlands. Single-nucleotide polymorphism and haplotype association analyses of a Dutch patient-control sample further supported the linkage at 7q36. In addition, we identified a shared haplotype at 7q36 between family 1270 and three of six multiplex AD-affected families from the same geographical region, which is indicative of a founder effect and defines a priority region of 9.3 cM. Mutation analysis of coding exons of 29 candidate genes identified one linked synonymous mutation, g.38030G-->C in exon 10, that affected codon 626 of the PAX transactivation domain interacting protein gene (PAXIP1). It remains to be determined whether PAXIP1 has a functional role in the expression of AD in family 1270 or whether another mutation at this locus explains the observed linkage and sharing. Together, our linkage data from the informative family 1270 and the association data in the population-based early-onset AD patient-control sample strongly support the identification of a novel AD locus at 7q36 and re-emphasize the genetic heterogeneity of AD.