Efficacy of Oxamyl Against Heterodera schachtii on Cabbage

The efficacy of oxamyl in controlling Heterodera schachtii on cabbage was determined by applying various contbinations of soil drenches at 6.7 kg (a.i.)/ha and foliar sprays at 0.04 kg (a.i.)/100 liters of water to cabbage seedlings. Pretransplant drenches provided some control of H. schachtii over a 13-week period. A single foliar spray of oxamyl 1 week before transplanting apparently prevented penetration of H. schachtii larvae; post-transplant sprays were relatively ineffective. A pretransplant or transplant drench combined with a foliar application 2 weeks after transplanting provided the most effective control. The effectiveness of drenches plus post-transplant sprays is probably due to the spray augmenting the action of the drench in inhibiting the development of larvae after penelration.     

Taurine kinetics assessed using [1,2-13C2]taurine in healthy adult humans

To assess the dynamics of taurine metabolism in vivo, two sets of studies were carried out in healthy volunteers. First, pilot studies were carried in a single human subject to determine the time course of plasma and whole blood isotope enrichment over the course of an 8-h, unprimed continuous infusion of [1,2-(13)C(2)]taurine. Second, five healthy adult males received two tracer infusions on separate days and in randomized order: 1) a 6-h continuous infusion of [1,2-(13)C(2)]taurine (3.1 +/- 0.2 micromol x kg(-1) x h(-1)) and 2) a bolus injection of [(13)C(2)]taurine (3.0 +/- 0.1 micromol/kg). Isotope enrichments in plasma and whole blood taurine were determined by gas chromatography-mass spectrometry. The pilot experiments allowed us to establish that steady-state isotope enrichment was reached in plasma and whole blood by the 5th h of tracer infusion. The plateau enrichment reached in whole blood was lower than that obtained in plasma taurine (P < 0.02). In the second set of studies, the appearance rate (R(a)) of plasma taurine, determined from continuous infusion studies was 31.8 +/- 3.1 micromol x kg(-1) x h(-1). After a bolus injection of tracer, the enrichment decay over the subsequent 2 h was best fitted by a two-exponential curve. Taurine R(a) was approximately 85% higher when determined using the bolus injection technique compared with continuous infusion of tracer. We conclude that 1) taurine R(a) into plasma is very low in healthy postabsorptive humans, and, due to taurine compartmentation between the extra- and intracellular milieus, may represent only interorgan taurine transfer and merely a small fraction of whole body taurine turnover; and 2) the bolus injection technique may overestimate taurine appearance into plasma. Further studies are warranted to determine whether alterations in bile taurine dynamics affect taurine R(a).     

Biphasic effect of protein kinase C activators on spontaneous and glucocorticoid-induced apoptosis in primary mouse thymocytes

Spontaneous and glucocorticoid (fluocinolone acetonide, FA)-induced apoptosis of primary mouse thymocytes was inhibited by protein kinase C (PKC) activators such as bryostatin-1 and phorbol ester 12-O-tetradecanoyl-phorbol-13 acetate (TPA) within the first 2-4 h of incubation but was enhanced upon prolonged treatment. Only the anti-apoptotic but not the pro-apoptotic effect of TPA was completely suppressed by the PKC inhibitor Goe 6983 and moderately inhibited by Goe 6976. Immunoblot analysis revealed distinct PKC alpha, beta, delta, eta, theta, mu and zeta signals, a very faint PKCepsilon and no PKCgamma signal. Upon prolonged TPA treatment all PKC isoenzymes became downregulated, albeit at different rates (PKCdelta>alpha>mu>beta,theta>eta,zeta). No significant generation of caspase-derived catalytic PKC fragments, as found to be produced upon induction of apoptosis and to be pro-apoptotic in other systems, was observed in FA- or TPA-treated thymocytes. It is concluded that the early anti-apoptotic effect of TPA depends on the activation of n-type PKC isoenzymes, whereas stimulation of spontaneous and FA-induced apoptosis by TPA ensues, at least partially, from a downregulation (or inactivation) of anti-apoptotic PKC species, i.e. in primary thymocytes PKC activation is primarily involved in a negative regulation of apoptosis.     

Agrobacterium tumefaciens virulence locus pscA is related to the Rhizobium meliloti exoC locus.

Agrobacterium tumefaciens and Rhizobium meliloti carry related genetic loci which have important roles in virulence and symbiosis. Previously, it was shown that two virulence loci of A. tumefaciens, chvA and chvB, are related to two R. meliloti symbiosis loci, ndvA and ndvB, respectively (T. Dylan, L. Ielpi, S. Stanfield, L. Kashyap, C. Douglas, M. Yanofsky, E. Nester, D. R. Helinski, and G. Ditta, Proc. Natl. Acad. Sci. USA 83:4403-4407, 1986). Here we show that these two phytobacteria possess additional related virulence/symbiosis genes. Results of genetic complementation and DNA hybridization experiments indicate that the pscA virulence locus of A. tumefaciens is structurally and functionally related to the exoC symbiosis locus of R. meliloti. Thus, A. tumefaciens and R. meliloti bear at least three related genetic loci that have crucial roles in establishing the interactions that each bacterium has with its respective host plants.     

Differential insulin responses to oral and intravenous glucose in the transplantable rat insulinoma--a role for GIP

We have previously demonstrated an impaired insulin response to intraperitoneal glucose and arginine by the transplantable NEDH rat insulinoma. The nature of this tumour B-cell defect has been further studied by investigating the response of insulinoma-bearing rats to intravenous and intragastric glucose. Intravenous glucose failed to stimulate plasma immunoreactive insulin (IRI) above high basal levels (14.5 +/- 1.1 micrograms/L). However, significant elevation of the plasma IRI concentration was observed following an intragastric glucose load (17.1 +/- 1.5 micrograms/L; P less than 0.02). In view of the different effects of oral and intravenous glucose on insulin secretion in the RIN, implicating an involvement of incretin factors from the gut, the response of the tumour to GIP was investigated. Plasma IRI concentrations rose significantly in these animals (20.6 +/- 2.5 micrograms/L at 5 min, P less than 0.02). We conclude that (a) the transplantable rat insulinoma is responsive to GIP, and (b) that whilst the tumour B-cell has lost its insulin responsiveness to hyperglycaemia produced by intraperitoneal or intravenous glucose, it retains its ability to respond to intragastric glucose. This could be due to incretin factors from the gut of which GIP is currently the strongest candidate.     

Roles of the GLABROUS1 and TRANSPARENT TESTA GLABRA Genes in Arabidopsis Trichome Development

Arabidopsis trichomes are branched, single-celled epidermal hairs. These specialized cells provide a convenient model for investigating the specification of cell fate in plants. Two key genes regulating the initiation of trichome development are GLABROUS1 (GL1) and TRANSPARENT TESTA GLABRA (TTG). GL1 is a member of the myb gene family. The maize R gene, which can functionally complement the Arabidopsis ttg mutation, encodes a basic helix-loop-helix protein. We used constitutively expressed copies of the GL1 and R genes to test hypotheses about the roles of GL1 and TTG in trichome development. The results support the hypothesis that TTG and GL1 cooperate at the same point in the trichome developmental pathway. Furthermore, the constitutive expression of both GL1 and R in the same plant caused trichomes to develop on all shoot epidermal surfaces. Results were also obtained indicating that TTG plays an additional role in inhibiting neighboring cells from becoming trichomes.     

Subcellular Localization of Rat Brain Insulin Binding Sites

Fractions and subcellular structures were prepared from rat brain homogenate and their purity was assessed using enzyme markers, gamma-aminobutyric acid binding, DNA content, and electron microscopy. Insulin binding was highest on the plasma membrane preparations and approximately 50% less so on brain homogenate crude mitochondrial (P2), myelinated axon, and synaptosome preparations. Very low levels of binding were found on mitochondria and nuclei. Differences in binding between fractions were due to numbers of binding sites, and not variable binding affinity. There was a close relationship between insulin binding and the activity of Na/K ATPase (E.C. 3.6.1.4) in all fractions (r = 0.98). Insulin binding to the P2 was compared with plasma membrane fractions in seven brain regions, and the results demonstrated the same close relationship between insulin binding and plasma membrane content in all regions except hypothalamus. Plasma membrane insulin binding was well represented by the binding on P2 membranes in all regions except hypothalamus and brainstem. It was concluded that insulin binding is distributed evenly over the surface of brain cells and is not increased on nerve endings.     

Identification of the synaptic vesicle glycoprotein 2 receptor binding site in botulinum neurotoxin A

Botulinum neurotoxins (BoNTs) inhibit neurotransmitter release by hydrolysing SNARE proteins. The most important serotype BoNT/A employs the synaptic vesicle glycoprotein 2 (SV2) isoforms A-C as neuronal receptors. Here, we identified their binding site by blocking SV2 interaction using monoclonal antibodies with characterised epitopes within the cell binding domain (H_C). The site is located on the backside of the conserved ganglioside binding pocket at the interface of the H_CC and H_CN subdomains. The dimension of the binding pocket was characterised in detail by site directed mutagenesis allowing the development of potent inhibitors as well as modifying receptor binding properties.     

Terrestrial basking sea turtles are responding to spatio-temporal sea surface temperature patterns

Naturalists as early as Darwin observed terrestrial basking in green turtles (Chelonia mydas), but the distribution and environmental influences of this behaviour are poorly understood. Here, we examined 6 years of daily basking surveys in Hawaii and compared them with the phenology of local sea surface temperatures (SST). Data and models indicated basking peaks when SST is coolest, and we found this timeline consistent with bone stress markings. Next, we assessed the decadal SST profiles for the 11 global green turtle populations. Basking generally occurs when winter SST falls below 23°C. From 1990 to 2014, the SST for these populations warmed an average 0.04°C yr⁻¹ (range 0.01–0.09°C yr⁻¹); roughly three times the observed global average over this period. Owing to projected future warming at basking sites, we estimated terrestrial basking in green turtles may cease globally by 2100. To predict and manage for future climate change, we encourage a more detailed understanding for how climate influences organismal biology.