Mechanisms of ATP release by human trabecular meshwork cells, the enabling step in purinergic regulation of aqueous humor outflow

Our guiding hypothesis is that ecto-enzymatic conversion of extracellular ATP to adenosine activates A(1) adenosine receptors, reducing resistance to aqueous humor outflow and intraocular pressure. The initial step in this purinergic regulation is ATP release from outflow-pathway cells by mechanisms unknown. We measured similar ATP release from human explant-derived primary trabecular meshwork (TM) cells (HTM) and a human TM cell line (TM5). Responses to 21 inhibitors indicated that pannexin-1 (PX1) and connexin (Cx) hemichannels and P2X(7) receptors (P2RX(7) ) were comparably important in modulating ATP release induced by hypotonic swelling, whereas vesicular release was insignificant. Consistent with prior studies of PX1 activity in certain other cells, ATP release was lowered by the reducing agent dithiothreitol. Overexpressing PX1 in HEK293T cells promoted, while partial knockdown (KD) in both HEK293T and TM5 cells inhibited hypotonicity-activated ATP release. Additionally, KD reduced the pharmacologically defined contribution of PX1 and enhanced those of Cx and P2RX(7) . ATP release was also triggered by raising intracellular Ca(2+) activity with ionomycin after a prolonged lag time and was unaffected by the PX1 blocker probenecid, but nearly abolished by P2RX(7) antagonists. We conclude that swelling-stimulated ATP release from human TM cells is physiologically mediated by PX1 and Cx hemichannels and P2X(7) receptors, but not by vesicular release. PX1 appears not to be stimulated by intracellular Ca(2+) in TM cells, but can be modulated by oxidation-reduction state. The P2RX(7) -dependent component of swelling-activated release may be mediated by PX1 hemichannels or reflect apoptotic magnification of ATP release, either through itself and/or hemichannels.     

Mgat1-dependent N-glycosylation of Membrane Components Primes Drosophila melanogaster Blood Cells for the Cellular Encapsulation Response

In nature, larvae of the fruitfly Drosophila melanogaster are commonly infected by parasitoid wasps, and so have evolved a robust immune response to counter wasp infection. In this response, fly immune cells form a multilayered capsule surrounding the wasp egg, leading to death of the parasite. Many of the molecular mechanisms underlying this encapsulation response are conserved with human immune responses. Our findings suggest that protein N-glycosylation, a common protein post-translational modification of human immune proteins, may be one such conserved mechanism. We found that membrane proteins on Drosophila immune cells are N-glycosylated in a temporally specific manner following wasp infection. Furthermore we have identified mutations in eight genes encoding enzymes of the N-glycosylation pathway that decrease fly resistance to wasp infection. More specifically, loss of protein N-glycosylation in immune cells following wasp infection led to the formation of defective capsules, which disintegrated over time and were thereby unsuccessful at preventing wasp development. Interestingly, we also found that one species of Drosophila parasitoid wasp, Leptopilina victoriae, targets protein N-glycosylation as part of its virulence mechanism, and that overexpression of an N-glycosylation enzyme could confer resistance against this wasp species to otherwise susceptible flies. Taken together, these findings demonstrate that protein N-glycosylation is a key player in Drosophila cellular encapsulation and suggest that this response may provide a novel model to study conserved roles of protein glycosylation in immunity.     

Potential contribution of natural enemies to patterns of local adaptation in plants

Genetic differentiation among plant populations and adaptation to local environmental conditions are well documented. However, few studies have examined the potential contribution of plant antagonists, such as insect herbivores and pathogens, to the pattern of local adaptation. Here, a reciprocal transplant experiment was set up at three sites across Europe using two common plant species, Holcus lanatus and Plantago lanceolata. The amount of damage by the main above-ground plant antagonists was measured: a rust fungus infecting Holcus and a specialist beetle feeding on Plantago, both in low-density monoculture plots and in competition with interspecific neighbours. Strong genetic differentiation among provenances in the amount of damage by antagonists in both species was found. Local provenances of Holcus had significantly higher amounts of rust infection than foreign provenances, whereas local provenances of Plantago were significantly less damaged by the specialist beetle than the foreign provenances. The presence of surrounding vegetation affected the amount of damage but had little influence on the ranking of plant provenances. The opposite pattern of population differentiation in resistance to local antagonists in the two species suggests that it will be difficult to predict the consequences of plant translocations for interactions with organisms of higher trophic levels.     

The Magelonidae (Annelida: Polychaeta) from the Seychelles, with the description of three new species

Three new species of Magelona are described from the Seychelles: M. conversa, M. falcifera and M. gemmata. Magelona conversa belongs to a 'M. mirabilisgroup', having a rounded prostomium and specialised chaetae on chaetiger 9, but differs from all other members in having long prechaetal neuropodial lamellae on chaetigers 1–8. Magelona falcifera bears large sickle-shaped hooded hooks in the abdomen and thus approaches the genus Meredithia, but lacks prostomial horns. Magelona gemmata belongs to a 'M. longicornis group' in having distinct prostomial frontal horns, and a thorax with lanceolate postchaetal lamellae in the notopodia and ventral neuropodial lobes. The distinctively swollen bud-like tips on the notopodial lamellae of chaetiger 9 are an unique feature. The status of MeredithiaHernández-Alcántara & Solís-Weiss, 2000 and current magelonid terminology are discussed.     

Prospective study of clinical,laboratory, and ancillary staff with accidental exposures to blood or body fluids from patients infected with HIV.

In a prospective study of 150 health care workers in the United Kingdom who had been accidentally exposed to the human immunodeficiency virus no evidence of transmission was found. Larger studies in the United States and anecdotal accounts in publications from other countries confirm that the risk of occupational infection is very low. Health care workers must adopt safe procedures at all times, however, to avoid exposure to infection.     

The cloning and over-expression of PABA synthase in E. coli

Both the genes encoding E. coli p-aminobenzoic acid synthase have been cloned and an overproducing strain has been obtained. The partial purification of the large subunit is described. The kinetic properties of the cloned enzyme, while similar to those reported for the B. subtilis enzyme, show some differences to those reported for the S. griseus enzyme.