Cross-modal identification: Effects of contingent changes in the stimulus series

Two computer controlled experiments in an olfactory cross-modal matching task, using two-component odour mixtures matched against bar diagrams, were designed so that stimulus presentation was contingent upon the recent performance of the subject; stimuli that were relatively poorly (in experiment 1) or well (in experiment 2) matched were more frequently presented. Analysis shows that the autoregressive structure of the performance is modified by such contingent presentation and that there is a weak relationship between transmitted information in matching and the time series structure of the matching errors. It is suggested that the process is nonlinear.     

Metabolism of cellular membrane sulpholipids in the rat brain

1. Metabolism of [(35)S]sulpholipid was studied in rats of different ages after the injection of [(35)S]sulphate. 2. The turnover of sulphatide in brain myelin and subcellular fractions was followed for long periods. 3. A small fraction of adult myelin underwent rapid metabolism, the rest being relatively metabolically stable. 4. Fast turnover of brain microsomal sulphatide during development was related to the process of myelination. 5. Turnover of mitochondrial sulphatide was at a lower rate than that calculated for liver mitochondria. 6. The relevance of the results to the metabolism of the whole membrane is discussed.     

Bronchus-associated lymphoid tissue (BALT) in the laboratory-bred and wild rat, Rattus norvegicus.

In juvenile wild rats, bronchus-associated lymphoid tissue (BALT) development was similar to that seen in adult specified-pathogen-free rats. In adult wild rats the BALT was widespread. In one animal infected with a mycoplasma-like organism, a region of bronchoepithelium overlying a large BALT nodule was seen, through which lymphocytes appeared able to pass to make direct contact with the bronchial lumen: the significance of this observation is discussed. There was no evidence of infection in lungs from any of the specified-pathogen-free animals, where small foci of BALT were seen.     

Selective mortality of a coral reef damselfish: role of predator–competitor synergisms

Phenotypic variability within cohorts of juvenile organisms can serve as the basis for selective mortality. Previous studies have demonstrated the important role that predators play in this process but not the impact of competitors on selective predation. We use a combination of lab and field studies to evaluate the effect of the presence of adult competitor damselfish (Dascyllus aruanus and Pomacentrus moluccensis; family Pomacentridae) on the selective mortality of newly-arrived (settled) lemon damselfish (P. moluccensis) by resident predator fishes (Pseudochromis fuscus Pseudochromidae and Cheilodipterus quinquelineatus Apogonidae). Lab trials consisted of mesocosm experiments in which the behaviour, mortality, and physiological condition (measured as lipid content) of surviving P. moluccensis settlers from each of three treatments: (1) predators absent, (2) predators present, and (3) predators and competitors present, were compared. The field study involved stocking newly settled P. moluccensis on natural bommies (patch reefs) which had either been subject to a partial removal of resident fish (predators and competitors) or left alone. Results indicated there was very strong condition-based selective mortality in both the lab and field trials. In both cases there was a strong positive relationship between mortality and the lipid content of surviving fish; implying low-condition fish were selectively removed. The mesocosm trials indicated that the strength of mortality as well as condition selectivity was higher when competitors were present than when they were absent. Behavioural observations in the mesocosm study suggest that attention by juvenile P. moluccensis to the movements and occasional chases of the competitors (especially D. aruanus) reduced their vigilance to the predators. These results suggest the important and interactive roles which condition of newly settled reef fish and interspecific competition can play in the outcomes of post-settlement predation. Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users.     

Protein expression in the obligate hydrocarbon-degrading psychrophile Oleispira antarctica RB-8 during alkane degradation and cold tolerance

In cold marine environments, the obligate hydrocarbon-degrading psychrophile Oleispira antarctica RB-8, which utilizes aliphatic alkanes almost exclusively as substrates, dominates microbial communities following oil spills. In this study, LC–MS/MS shotgun proteomics was used to identify changes in the proteome induced during growth on n-alkanes and in cold temperatures. Specifically, proteins with significantly higher relative abundance during growth on tetradecane (n-C₁₄) at 16°C and 4°C have been quantified. During growth on n-C₁₄, O. antarctica expressed a complete pathway for the terminal oxidation of n-alkanes including two alkane monooxygenases, two alcohol dehydrogenases, two aldehyde dehydrogenases, a fatty-acid-CoA ligase, a fatty acid desaturase and associated oxidoreductases. Increased biosynthesis of these proteins ranged from 3- to 21-fold compared with growth on a non-hydrocarbon control. This study also highlights mechanisms O. antarctica may utilize to provide it with ecological competitiveness at low temperatures. This was evidenced by an increase in spectral counts for proteins involved in flagella structure/output to overcome higher viscosity, flagella rotation to accumulate cells and proline metabolism to counteract oxidative stress, during growth at 4°C compared with 16°C. Such species-specific understanding of the physiology during hydrocarbon degradation can be important for parameterizing models that predict the fate of marine oil spills.     

Role of ultrasonography in diagnosing early rheumatoid arthritis and remission of rheumatoid arthritis - a systematic review of the literature

Introduction

Ultrasonography (US) might have an added value to clinical examination in diagnosing early rheumatoid arthritis (RA) and assessing remission of RA. We aimed to clarify the added value of US in RA in these situations performing a systematic review.

Methods

A systematic literature search was performed for RA, US, diagnosis and remission. Methodological quality was assessed; the wide variability in the design of studies prohibited pooling of results.

Results

Six papers on the added value of US diagnosing early RA were found, in which at least bilateral metacarpophalangeal (MCP), wrists and metatarsophalangeal (MTP) joints were scanned. Compared to clinical examination, US was superior with regard to detecting synovitis and predicting progression to persistent arthritis or RA. Eleven papers on assessing remission were identified, in which at least the wrist and the MCP joints of the dominant hand were scanned. Often US detected inflammation in patients clinically in remission, irrespective of the remission criteria used. Power Doppler signs of synovitis predicted X-ray progression and future flare in patients clinically in remission.

Conclusions

US appears to have added value to clinical examination for diagnosing of RA when scanning at least MCP, wrist and MTP joints, and, when evaluating remission of RA, scanning at least wrist and MCP joints of the dominant hand. For both purposes primarily power Doppler US might be used since its results are less equivocal than those of greyscale US.     

Fish Assemblages on Estuarine Artificial Reefs: Natural Rocky-Reef Mimics or Discrete Assemblages?

If the primary goal of artificial reef construction is the creation of additional reef habitat that is comparable to adjacent natural rocky-reef, then performance should be evaluated using simultaneous comparisons with adjacent natural habitats. Using baited remote underwater video (BRUV) fish assemblages on purpose-built estuarine artificial reefs and adjacent natural rocky-reef and sand-flat were assessed 18 months post-deployment in three south-east Australian estuaries. Fish abundance, species richness and diversity were found to be greater on the artificial reefs than on either naturally occurring reef or sand-flat in all estuaries. Comparisons within each estuary identified significant differences in the species composition between the artificial and natural rocky-reefs. The artificial reef assemblage was dominated by sparid species including Acanthopagrus australis and Rhabdosargus sarba. The preference for a range of habitats by theses sparid species is evident by their detection on sand-flat, natural rocky reef and artificial reef habitats. The fish assemblage identified on the artificial reefs remained distinct from the adjacent rocky-reef, comprising a range of species drawn from naturally occurring rocky-reef and sand-flat. In addition, some mid-water schooling species including Trachurus novaezelandiae and Pseudocaranx georgianus were only identified on the artificial reef community; presumably as result of the reef''s isolated location in open-water. We concluded that estuarine artificial reef assemblages are likely to differ significantly from adjacent rocky-reef, potentially as a result of physical factors such as reef isolation, coupled with species specific behavioural traits such as the ability of some species to traverse large sand flats in order to locate reef structure, and feeding preferences. Artificial reefs should not be viewed as direct surrogates for natural reef. The assemblages are likely to remain distinct from naturally occurring habitat comprised of species that reside on a range of adjacent natural habitats.     

Increasing Adolescent HIV Prevalence in Eastern Zimbabwe – Evidence of Long-Term Survivors of Mother-to-Child Transmission?

Recent data from the Manicaland HIV/STD Prevention Project, a general-population open HIV cohort study, suggested that between 2004 and 2007 HIV prevalence amongst males aged 15–17 years in eastern Zimbabwe increased from 1.20% to 2.23%, and in females remained unchanged at 2.23% to 2.39%, while prevalence continued to decline in the rest of the adult population. We assess whether the more likely source of the increase in adolescent HIV prevalence is recent sexual HIV acquisition, or the aging of long-term survivors of perinatal HIV acquisition that occurred during the early growth of the epidemic. Using data collected between August 2006 and November 2008, we investigated associations between adolescent HIV and (1) maternal orphanhood and maternal HIV status, (2) reported sexual behaviour, and (3) reporting recurring sickness or chronic illness, suggesting infected adolescents might be in a late stage of HIV infection. HIV-infected adolescent males were more likely to be maternal orphans (RR = 2.97, p<0.001) and both HIV-infected adolescent males and females were more likely to be maternal orphans or have an HIV-infected mother (male RR = 1.83, p<0.001; female RR = 16.6, p<0.001). None of 22 HIV-infected adolescent males and only three of 23 HIV-infected females reported ever having had sex. HIV-infected adolescents were 60% more likely to report illness than HIV-infected young adults. Taken together, all three hypotheses suggest that recent increases in adolescent HIV prevalence in eastern Zimbabwe are more likely attributable to long-term survival of mother-to-child transmission rather than increases in risky sexual behaviour. HIV prevalence in adolescents and young adults cannot be used as a surrogate for recent HIV incidence, and health systems should prepare for increasing numbers of long-term infected adolescents.