Responses of coral and fish assemblages to a severe but short-lived tropical cyclone on the Great Barrier Reef,Australia

Changes in reef assemblages of corals and fishes following a tropical cyclone were assessed using data sets from (1) manta tow surveys of entire reef perimeters and (2) intensive surveys of specific sites, across 11 reefs lying close to the cyclone's track. Only one of the reefs experienced an obvious and immediate decline in mean coral cover (from 24 to 8%) due to the cyclone. The abundance and species richness of adult damselfish assemblages on intensive survey sites at this reef were not affected in the short term (6-8 weeks), despite the removal of 48% of living hard coral. Assemblages of adult fishes showed a similar lack of response at three other reefs where no significant habitat changes had occurred. Eleven to twelve months later, the total abundance of damselfishes had decreased substantially at eight of the sampled reefs, while the abundance of larger mobile fishes remained stable. We infer that the effects on coral assemblages reflect the short duration and orientation of the cyclone, the history of exposure to wave energy (influencing life-form structure and therefore degree of fragility), and the degree of consolidation of the reef matrix. The lack of short-term effects of the cyclone on adult fishes shows that these fishes can endure periods of intense underwater turbulence. The lack of change in damselfish assemblages weeks after loss of coral cover implies that this resource was not limiting adult fish densities. The reasons for widespread decreases in damselfish numbers 11-12 months after the cyclone are unknown.     

Physical mapping identifies DXS265 as a useful genetic marker for carrier detection and prenatal diagnosis of X-linked agammaglobulinemia

The gene responsible for X-linked agammaglobulinemia (XLA) has not been identified; however, in the course of genetic linkage studies designed to map the locus more precisely, a number of closely linked polymorphic loci have been identified. These have proved to be useful in identifying carriers and in pre-natal diagnosis of this disease. The DXS178 locus was found to be closest to the XLA locus and has been the most usefully employed probe to date. Using physical mapping techniques, we have identified a previously cloned genetic marker, DXS265, as being situated within 5kb of DXS178. So far, we have found one family that is not informative for DXS178 but that is informative for DXS265; females in this family can now be offered the possibility of carrier determination and pre-natal diagnosis for this life-threatening disease.     

Dimers of the Neuropeptide Y (NPY) Y2 Receptor Show Asymmetry in Agonist Affinity and Association with G Proteins

In conditions precluding activation of G proteins, the binding of agonists to dimers of the neuropeptide Y (NPY) Y2 receptor shows two components of similar size, but differing in affinity. The dimers of all NPY receptors are solubilized as ～ 180-kDa complexes containing one G protein α β γ trimer. These heteropentamers are stable to excess agonists, chelators, and alkylators. However, dispersion in the weak surfactant cholate releases ～ 300-kDa complexes. These findings indicate that both protomers in the Y2 dimer are associated with G protein heterotrimers, but the extent of interaction depends on affinity for the agonist peptide. The G protein in contact with the first-liganded, higher-affinity protomer should have a stronger interaction with the receptor and a larger probability of activation.     

Type I interferon is required for T helper (Th) 2 induction by dendritic cells

Type 2 inflammation is a defining feature of infection with parasitic worms (helminths), as well as being responsible for widespread suffering in allergies. However, the precise mechanisms involved in T helper (Th) 2 polarization by dendritic cells (DCs) are currently unclear. We have identified a previously unrecognized role for type I IFN (IFN‐I) in enabling this process. An IFN‐I signature was evident in DCs responding to the helminth Schistosoma mansoni or the allergen house dust mite (HDM). Further, IFN‐I signaling was required for optimal DC phenotypic activation in response to helminth antigen (Ag), and efficient migration to, and localization with, T cells in the draining lymph node (dLN). Importantly, DCs generated from Ifnar1^?/? mice were incapable of initiating Th2 responses in vivo. These data demonstrate for the first time that the influence of IFN‐I is not limited to antiviral or bacterial settings but also has a central role to play in DC initiation of Th2 responses.     

The threat to coral reefs from more intense cyclones under climate change

Ocean warming under climate change threatens coral reefs directly, through fatal heat stress to corals and indirectly, by boosting the energy of cyclones that cause coral destruction and loss of associated organisms. Although cyclone frequency is unlikely to rise, cyclone intensity is predicted to increase globally, causing more frequent occurrences of the most destructive cyclones with potentially severe consequences for coral reef ecosystems. While increasing heat stress is considered a pervasive risk to coral reefs, quantitative estimates of threats from cyclone intensification are lacking due to limited data on cyclone impacts to inform projections. Here, using extensive data from Australia's Great Barrier Reef (GBR), we show that increases in cyclone intensity predicted for this century are sufficient to greatly accelerate coral reef degradation. Coral losses on the outer GBR were small, localized and offset by gains on undisturbed reefs for more than a decade, despite numerous cyclones and periods of record heat stress, until three unusually intense cyclones over 5 years drove coral cover to record lows over >1500 km. Ecological damage was particularly severe in the central‐southern region where 68% of coral cover was destroyed over >1000 km, forcing record declines in the species richness and abundance of associated fish communities, with many local extirpations. Four years later, recovery of average coral cover was relatively slow and there were further declines in fish species richness and abundance. Slow recovery of community diversity appears likely from such a degraded starting point. Highly unusual characteristics of two of the cyclones, aside from high intensity, inflated the extent of severe ecological damage that would more typically have occurred over 100s of km. Modelling published predictions of future cyclone activity, the likelihood of more intense cyclones within time frames of coral recovery by mid‐century poses a global threat to coral reefs and dependent societies.     

Pathways and products for the metabolism of vitamin D3 by cytochrome P450scc

Cytochrome P450scc (CYP11A1) can hydroxylate vitamin D3 to produce 20-hydroxyvitamin D3 and other poorly characterized hydroxylated products. The present study aimed to identify all the products of vitamin D3 metabolism by P450scc, as well as the pathways leading to their formation. Besides 20-hydroxyvitamin D3, other major metabolites of vitamin D3 were a dihydroxyvitamin D3 and a trihydroxyvitamin D3 product. The dihydroxyvitamin D3 was clearly identified as 20,23-dihydroxyvitamin D3 by NMR, in contrast to previous reports that postulated hydroxyl groups in positions 20 and 22. NMR of the trihydroxy product identified it as 17alpha,20,23-trihydroxyvitamin D3. This product could be directly produced by P450scc acting on 20,23-dihydroxyvitamin D3, confirming that hydroxyl groups are present at positions 20 and 23. Three minor products of D3 metabolism by P450scc were identified by MS and by examining their subsequent metabolism by P450scc. These products were 23-hydroxyvitamin D3, 17alpha-hydroxyvitamin D3 and 17alpha,20-dihydroxyvitamin D3 and arise from the three P450scc-catalysed hydroxylations occurring in a different order. We conclude that the major pathway of vitamin D3 metabolism by P450scc is: vitamin D3 --> 20-hydroxyvitamin D3 --> 20,23-dihydroxyvitamin D3 --> 17alpha,20,23-trihydroxyvitamin D3. The major products dissociate from the P450scc active site and accumulate at a concentration well above the P450scc concentration. Our new identification of the major dihydroxyvitamin D3 product as 20,23-dihydroxyvitamin D3, rather than 20,22-dihydroxyvitamin D3, explains why there is no cleavage of the vitamin D3 side chain, unlike the metabolism of cholesterol by P450scc.     

The neuropeptide Y (NPY) Y2 receptors are largely dimeric in the kidney, but monomeric in the forebrain

The neuropeptide Y(NPY) Y2 receptors are detected largely as dimers in the clonal expressions in CHO cells and in particulates from rabbit kidney cortex. However, in two areas of the forebrain (rat or rabbit piriform cortex and hypothalamus), these receptors are found mainly as monomers. Evidence is presented that this difference relates to large levels of G proteins containing the Gi alpha -subunit in the forebrain areas. The predominant monomeric status of these Y2 receptors should also be physiologically linked to large synaptic inputs of the agonist NPY. The rabbit kidney and the human CHO cell-expressed Y2 dimers are converted by agonists to monomers in vitro at a similar rate in the presence of divalent cations.     

Management of Calving in Norwegian Cubicle-Housed Dairy Herds

Sixty of the 65 dairy farms with cubicle houses in the Norwegian county of Oppland were included in a field study of the management of calving in 1990. The farmers recorded the location of the cow when giving birth, farmer presence and whether assistance was given during calving, occurrence of suckling, and time after birth when cow and calf were separated. Such data were recorded for a total of 1125 calvings. About 10% occurred on pasture, while 78% of the remaining calvings took place in the cubicle-equipped section. Thirteen percent calved in a calving pen, the remaining cows being tethered at the time of calving. Thirty-two percent of the calvings took place in houses lacking a calving pen altogether. Farmers were present during 41% of the calvings. Suckling most frequently occurred after pasture calvings, and was least frequent after calvings within the cubicle-equipped section of the cowhouse. Injuries to the calf caused by trampling or contact with fittings etc. were rare, and no more common in association with calving in the cubicle-equipped section than with calving taking place with the cow isolated from the rest of the herd. All calves were removed from their dams within 24 h after birth.     

Chronic exposure of diesel exhaust particles induces alveolar enlargement in mice

Background

Diesel exhaust particles (DEPs) are deposited into the respiratory tract and are thought to be a risk factor for the development of diseases of the respiratory system. In healthy individuals, the timing and mechanisms of respiratory tract injuries caused by chronic exposure to air pollution remain to be clarified.

Methods

We evaluated the effects of chronic exposure to DEP at doses below those found in a typical bus corridor in Sao Paulo (150 μg/m³). Male BALB/c mice were divided into mice receiving a nasal instillation: saline (saline; n = 30) and 30 μg/10 μL of DEP (DEP; n = 30). Nasal instillations were performed five days a week, over a period of 90 days. Bronchoalveolar lavage (BAL) was performed, and the concentrations of interleukin (IL)-4, IL-10, IL-13 and interferon-gamma (INF-γ) were determined by ELISA-immunoassay. Assessment of respiratory mechanics was performed. The gene expression of Muc5ac in lung was evaluated by RT-PCR. The presence of IL-13, MAC2+ macrophages, CD3+, CD4+, CD8+ T cells and CD20+ B cells in tissues was analysed by immunohistochemistry. Bronchial thickness and the collagen/elastic fibers density were evaluated by morphometry. We measured the mean linear intercept (Lm), a measure of alveolar distension, and the mean airspace diameter (D0) and statistical distribution (D2).

Results

DEP decreased IFN-γ levels in BAL (p = 0.03), but did not significantly alter IL-4, IL-10 and IL-13 levels. MAC2+ macrophage, CD4+ T cell and CD20+ B cell numbers were not altered; however, numbers of CD3+ T cells (p ≤ 0.001) and CD8+ T cells (p ≤ 0.001) increased in the parenchyma. Although IL-13 (p = 0.008) expression decreased in the bronchiolar epithelium, Muc5ac gene expression was not altered in the lung of DEP-exposed animals. Although respiratory mechanics, elastic and collagen density were not modified, the mean linear intercept (Lm) was increased in the DEP-exposed animals (p ≤ 0.001), and the index D2 was statistically different (p = 0.038) from the control animals.

Conclusion

Our data suggest that nasal instillation of low doses of DEP over a period of 90 days results in alveolar enlargement in the pulmonary parenchyma of healthy mice.

Electronic supplementary material

The online version of this article (doi:10.1186/s12931-015-0172-z) contains supplementary material, which is available to authorized users.