Immunoreactivity of the <Emphasis Type="Italic">Mycobacterium avium</Emphasis> subsp. <Emphasis Type="Italic">paratuberculosis</Emphasis> 19-kDa lipoprotein

Background  

The Mycobacterium tuberculosis 19-kDa lipoprotein has been reported to stimulate both T and B cell responses as well as induce a number of Th1 cytokines. In order to evaluate the Mycobacterium avium subsp. paratuberculosis (M. avium subsp. paratuberculosis) 19-kDa lipoprotein as an immunomodulator in cattle with Johne's disease, the gene encoding the 19-kDa protein (MAP0261c) was analyzed.     

Asn 362 in gp120 contributes to enhanced fusogenicity by CCR5-restricted HIV-1 envelope glycoprotein variants from patients with AIDS

Background

CCR5-restricted (R5) human immunodeficiency virus type 1 (HIV-1) variants cause CD4+ T-cell loss in the majority of individuals who progress to AIDS, but mechanisms underlying the pathogenicity of R5 strains are poorly understood. To better understand envelope glycoprotein (Env) determinants contributing to pathogenicity of R5 viruses, we characterized 37 full-length R5 Envs from cross-sectional and longitudinal R5 viruses isolated from blood of patients with asymptomatic infection or AIDS, referred to as pre-AIDS (PA) and AIDS (A) R5 Envs, respectively.

Results

Compared to PA-R5 Envs, A-R5 Envs had enhanced fusogenicity in quantitative cell-cell fusion assays, and reduced sensitivity to inhibition by the fusion inhibitor T-20. Sequence analysis identified the presence of Asn 362 (N362), a potential N-linked glycosylation site immediately N-terminal to CD4-binding site (CD4bs) residues in the C3 region of gp120, more frequently in A-R5 Envs than PA-R5 Envs. N362 was associated with enhanced fusogenicity, faster entry kinetics, and increased sensitivity of Env-pseudotyped reporter viruses to neutralization by the CD4bs-directed Env mAb IgG1b12. Mutagenesis studies showed N362 contributes to enhanced fusogenicity of most A-R5 Envs. Molecular models indicate N362 is located adjacent to the CD4 binding loop of gp120, and suggest N362 may enhance fusogenicity by promoting greater exposure of the CD4bs and/or stabilizing the CD4-bound Env structure.

Conclusion

Enhanced fusogenicity is a phenotype of the A-R5 Envs studied, which was associated with the presence of N362, enhanced HIV-1 entry kinetics and increased CD4bs exposure in gp120. N362 contributes to fusogenicity of R5 Envs in a strain dependent manner. Our studies suggest enhanced fusogenicity of A-R5 Envs may contribute to CD4+ T-cell loss in subjects who progress to AIDS whilst harbouring R5 HIV-1 variants. N362 may contribute to this effect in some individuals.     

Monthly day/night changes and seasonal daily rhythms of sexual steroids in Senegal sole (Solea senegalensis) under natural fluctuating or controlled environmental conditions

In this paper we attempted to investigate the existence of daily fluctuations on plasma sexual steroids (17beta-estradiol, E(2) and testosterone, T) in Senegal sole (Solea senegalensis) females. We described the monthly day/night concentrations and seasonal daily rhythms in animals reared under natural photo- and thermo-period. In addition, the influence of the natural annual fluctuation of the water temperature on the plasma concentration of these steroids was investigated, using one group of Senegal sole under a natural photoperiod, but with an attenuated thermal cycle (around 17-20 degrees C) for one year. Although no significant day/night differences were detected in monthly samplings, the existence of an annual rhythm of E(2) and T (p<0.01) with an acrophase in February was revealed by COSINOR analysis. Maximum values were reached in March for both steroids (6.1+/-1.7 ng mL(-1) at mid-dark, MD and 4.0+/-0.6 ng mL(-1) at mid-light, ML for E2 and 1.4+/-0.4 ng mL(-1) at MD and 0.8+/-0.1 ng mL(-1) at ML for T) in anticipation of the spawning season (May-June). As regards seasonal daily rhythms, the presence of daily oscillations was revealed. At the spring solstice (21st March) a daily rhythm was observed for both steroids (COSINOR, p<0.01), with an acrophase at 20:00 h (E(2)) and at 21:08 h (T). In summer, autumn and winter no daily rhythms were observed due to the low steroid levels at those seasons. When Senegal sole females were submitted to an attenuated annual thermal cycle, the steroid rhythm disappeared (there was no surge in spring, as in the control group) and these fish did not spawn, despite being subjected to natural photoperiod conditions. This result underlined the importance of the natural annual fluctuation of water temperature and photoperiod on the synchronization of the spawning season and on the onset of steroidogenesis.     

Defensive insect symbiont leads to cascading extinctions and community collapse

Animals often engage in mutualistic associations with microorganisms that protect them from predation, parasitism or pathogen infection. Studies of these interactions in insects have mostly focussed on the direct effects of symbiont infection on natural enemies without studying community‐wide effects. Here, we explore the effect of a defensive symbiont on population dynamics and species extinctions in an experimental community composed of three aphid species and their associated specialist parasitoids. We found that introducing a bacterial symbiont with a protective (but not a non‐protective) phenotype into one aphid species led to it being able to escape from its natural enemy and increase in density. This changed the relative density of the three aphid species which resulted in the extinction of the two other parasitoid species. Our results show that defensive symbionts can cause extinction cascades in experimental communities and so may play a significant role in the stability of consumer‐herbivore communities in the field.     

Novel mass spectrometric immunoassays for the rapid structural characterization of plasma apolipoproteins

Novel mass spectrometric immunoassays (MSIAs) for the isolation and structural characterization of plasma apolipoprotein A-I (apoA-I), apoA-II, and apoE have been developed. The assays combine selective isolation of apolipoprotein species via affinity capture with mass-specific detection using matrix-assisted laser desorption/ionization time-of-flight mass spectrometry. In application, plasma (from 50 microl of whole blood drawn from individuals, using finger lancet) was addressed with affinity pipette tips derivatized with antibodies toward the specific apolipoprotein. The time required for each assay was approximately 15 min, less if assays on multiple individuals were performed in parallel. In a brief study of five individuals, several recently reported apoA-II variants were identified and observed consistently in all individuals. Additionally, the apoE phenotype of E3/E3 was observed in three of the individuals, and E2/E3 and E3/E4 observed in the remaining two individuals, the latter of whom suffers from Alzheimer's disease. Overall, the MSIA approach offers a rapid, sensitive, and highly accurate means of profiling apolipoproteins from small volumes of plasma.     

Muscle development in dendrobranchiate shrimp, with comparison with Artemia

The muscle pattern of malacostracan and entomostracan crustacean nauplius larvae was compared using fluorescent phallotoxins. In the dendrobranchiate malacostracan Sicyonia ingentis, F-actin staining was first detected in limb setae at 12 h, likely within sensory nerves. Staining of F-actin was detected in the trunk at 15 h and grew into the naupliar limbs. Sarcomeres were detected at 19 h, identifying the structures as extrinsic limb muscles. The extrinsic limb muscles enlarged but retained their general pattern during the later nauplius stages. Longitudinal trunk muscles and circumferential visceral muscle (VM) developed in the post-naupliar region during nauplius instars 4 and 5, at the time when the gut also formed. In the anostracan branchiopod Artemia salina, the newly hatched nauplius contained an extensive system of extrinsic and intrinsic limb muscles. The gut was almost complete at hatching, along with its associated circumferential VM. Muscles similar in position and structure could be identified in nauplii from the two taxa, but different anatomical origins of extrinsic muscles were evident. Whether the naupliar limb muscles are homologous in malacostracans and branchiopods remains an open question. The strong musculature of the dendrobranchiate naupliar limbs correlates with the use of all three pairs of limbs for swimming.     

The effect of molybdenum on the molecular control of cold tolerance in cauliflower (Brassica oleracea var. botrytis) artificial seeds

Molybdenum (Mo) was used to improve the cold tolerance of cauliflower microshoots/artificial seeds. The optimal stage to introduce Mo to the micropropagation system was found to be the microshoots liquid culture stage, since its use within artificial seed capsules or conversion media had negative effects on conversion rate and viability. Mo was found to improve the cold tolerance of both acclimated and non-acclimated microshoots/artificial seeds. The capacity of Mo to up-regulate CBF/DREB1 in cauliflower microshoots was confirmed. Moreover, this study is the first to confirm the ability of this element to up-regulate CBF/DREB1 without any low temperature treatment. Mo significantly increased the accumulation of 23 kDa polypeptide when it was used at 15 ppm concentration. However, Mo had a negative effect on the accumulation of dehydrin proteins which suggest that this group of proteins have no significant role in the cold tolerance of cauliflower microshoots. The study could help in improving the understanding of the abiotic stress network in plants and in improving the quality and efficiency of cauliflower artificial seed production systems.     

Bucking the trend of pollinator decline: the population genetics of a range expanding bumblebee

Evolutionary Ecology - Recent research has shown drastic reductions in the global diversity and abundance of insects. This is a major concern given the expected cascade effects on ecosystem...     

Exploratory Hydrocarbon Drilling Impacts to Arctic Lake Ecosystems

Recent attention regarding the impacts of oil and gas development and exploitation has focused on the unintentional release of hydrocarbons into the environment, whilst the potential negative effects of other possible avenues of environmental contamination are less well documented. In the hydrocarbon-rich and ecologically sensitive Mackenzie Delta region (NT, Canada), saline wastes associated with hydrocarbon exploration have typically been disposed of in drilling sumps (i.e., large pits excavated into the permafrost) that were believed to be a permanent containment solution. However, failure of permafrost as a waste containment medium may cause impacts to lakes in this sensitive environment. Here, we examine the effects of degrading drilling sumps on water quality by combining paleolimnological approaches with the analysis of an extensive present-day water chemistry dataset. This dataset includes lakes believed to have been impacted by saline drilling fluids leaching from drilling sumps, lakes with no visible disturbances, and lakes impacted by significant, naturally occurring permafrost thaw in the form of retrogressive thaw slumps. We show that lakes impacted by compromised drilling sumps have significantly elevated lakewater conductivity levels compared to control sites. Chloride levels are particularly elevated in sump-impacted lakes relative to all other lakes included in the survey. Paleolimnological analyses showed that invertebrate assemblages appear to have responded to the leaching of drilling wastes by a discernible increase in a taxon known to be tolerant of elevated conductivity coincident with the timing of sump construction. This suggests construction and abandonment techniques at, or soon after, sump establishment may result in impacts to downstream aquatic ecosystems. With hydrocarbon development in the north predicted to expand in the coming decades, the use of sumps must be examined in light of the threat of accelerated permafrost thaw, and the potential for these industrial wastes to impact sensitive Arctic ecosystems.