Shift work and mortality

Despite results linking shift work with ill health, only a few studies have addressed its relation with mortality. The purpose of the present study was to examine the hypothesis that shift work is a predictor of mortality. The study involved a sample of 22,411 individuals of the Swedish population. Data were obtained through annual phone interviews done between 1979 and 2000. Cox regression analysis was used to assess the association between shift work/day work as the independent variable and death/survival during the subsequent years as the dependent variable. Separate analyses were carried out for female and male white- and blue-collar workers, respectively. The results were adjusted for age, stress, physical work load, disease at the outset of the study, and smoking. Mortality was significantly increased for female white-collar workers, with a Hazard Ratio of 2.61 and a 95% confidence interval of 1.26-5.41. No other significant effects were found. It is concluded that blue-collar shift work is not related to mortality, but that risk of death is increased for women white-collar shift workers compared to women white-collar day workers.     

Evaluation of two pairs of chiral stationary phases: effects from the length of the achiral spacers

Two pairs of chiral stationary phases (CSPs) with different C(2)-symmetric central parts were prepared and evaluated by chromatography of a series of structurally different racemates. Within each pair, the selectors on which the CSPs are based had different lengths of their achiral spacers. The CSPs based on selectors with short spacers showed higher enantioselectivity than the phases incorporating long spacers. On one pair of the phases, a study of the influence from different retention modifiers was performed for a series of benzodiazepinones. This demonstrated the importance of the polymer structure formed from the selectors with different spacer lengths for the enantiodiscriminating ability of the CSPs.     

Classification of G-protein coupled receptors by alignment-independent extraction of principal chemical properties of primary amino acid sequences

We have developed an alignment-independent method for classification of G-protein coupled receptors (GPCRs) according to the principal chemical properties of their amino acid sequences. The method relies on a multivariate approach where the primary amino acid sequences are translated into vectors based on the principal physicochemical properties of the amino acids and transformation of the data into a uniform matrix by applying a modified autocross-covariance transform. The application of principal component analysis to a data set of 929 class A GPCRs showed a clear separation of the major classes of GPCRs. The application of partial least squares projection to latent structures created a highly valid model (cross-validated correlation coefficient, Q(2) = 0.895) that gave unambiguous classification of the GPCRs in the training set according to their ligand binding class. The model was further validated by external prediction of 535 novel GPCRs not included in the training set. Of the latter, only 14 sequences, confined in rapidly expanding GPCR classes, were mispredicted. Moreover, 90 orphan GPCRs out of 165 were tentatively identified to GPCR ligand binding class. The alignment-independent method could be used to assess the importance of the principal chemical properties of every single amino acid in the protein sequences for their contributions in explaining GPCR family membership. It was then revealed that all amino acids in the unaligned sequences contributed to the classifications, albeit to varying extent; the most important amino acids being those that could also be determined to be conserved by using traditional alignment-based methods.     

Exploring species boundaries with multiple genetic loci using empirical data from non‐biting midges

Over the past decade, molecular approaches to species delimitation have seen rapid development. However, species delimitation based on a single locus, for example, DNA barcodes, can lead to inaccurate results in cases of recent speciation and incomplete lineage sorting. Here, we compare the performance of Automatic Barcode Gap Discovery (ABGD), Bayesian Poisson tree processes (PTP), networks, generalized mixed Yule coalescent (GMYC) and Bayesian phylogenetics and phylogeography (BPP) models to delineate cryptic species previously detected by DNA barcodes within Tanytarsus (Diptera: Chironomidae) non‐biting midges. We compare the results from analyses of one mitochondrial (cytochrome c oxidase subunit I [COI]) and three nuclear (alanyl‐tRNA synthetase 1 [AATS1], carbamoyl phosphate synthetase 1 [CAD1] and 6‐phosphogluconate dehydrogenase [PGD]) protein‐coding genes. Our results show that species delimitation based on multiple nuclear DNA markers is largely concordant with morphological variation and delimitations using a single locus, for example, the COI barcode. However, ABGD, GMYC, PTP and network models led to conflicting results based on a single locus and delineate species differently than morphology. Results from BPP analyses on multiple loci correspond best with current morphological species concept. In total, 10 lineages of the Tanytarsus curticornis species complex were uncovered. Excluding a Norwegian population of Tanytarsus brundini which might have undergone recent hybridization, this suggests six hitherto unrecognized species new to science. Five distinct species are well supported in the Tanytarsus heusdensis species complex, including two species new to science.     

Spectroscopic studies of cobalt-substituted ferredoxin fromClostridium pasteurianum

Summary Ferredoxin fromClostridium pasteurianum substituted with two Co atoms did not give any cobalt EPR signal at 8 K as isolated, but upon reduction with sodium dithionite, a broad signal appeared withg values that indicate highspin (S=3/2) Co(II). These signals were distinct from Co(II)-dithiothreitol signals, and disappeared upon reoxidation with air. Under anaerobic incubation of apoferredoxin with Co(II), a green derivative showed a visible spectrum typical of tetrahedral Co(Il)-thiolate coordination, which shifted dramatically upon exposure to air. The¹H-NMR spectrum of the aerobically isolated protein is reported at 300 MHz; magnetic susceptibility measurements were indicative of a diamagnetic species. These spectroscopic studies indicate that Co(II)-substituted ferredoxin is oxidized to low-spin Co(III)-ferredoxin in the presence of sulfide and oxygen. The diamagnetic Co(III) state could reversibly be reduced to highspin Co(II) by sodium dithionite.     

MHC variation in birds and reptiles

The major histocompatibility complex (MHC) has been studied in a multitude of mammals by now, but much less is known about its organisation and variation in other vertebrate species. The mammalian MHC is organised as a single gene cluster, but recent studies on birds suggest that this paradigm of MHC organisation has to be supplemented. The domestic chicken thus possesses two separate gene clusters which both contain MHC class I and class II B genes, and we have shown that the ring‐necked pheasant Phasianus colchicus also has two unlinked clusters of class II B genes. We are studying the effect of the MHC on mate choice, survival and reproductive success in natural populations of birds and reptiles. For this reason, we are developing DNA techniques to determine the animals' MHC genotype. The amplification of the hypervariable exon 3 of the class I gene from songbirds and reptiles has provided us with species specific probes that can be used in Southern blot analysis. The first results indicate very extensive variation in all studied species, that is starlings Sturnus vulgaris, great reed warblers Acrocephalus arundinaceus and water pythons Liasis fuscus. The restriction fragment length polymorphism (RFLP) analysis also suggests that the number of MHC genes is significantly larger in these species than in pheasants and domestic chickens. This revised version was published online in July 2006 with corrections to the Cover Date.     

Effects of bicarbonate and oxygen concentration on photoinhibition of thylakoid membranes

The effects of bicarbonate and oxygen on photoinhibition of thylakoid membranes were investigated by varying their concentrations independently of each other. A pretreatment of the thylakoid suspension which lowered the bicarbonate concentration of the medium without affecting its oxygen content, increased the degree of photoinhibition upon illumination. This showed that the normal bicarbonate content of a thylakoid suspension, originating from dissolved carbondioxide from the air, protects against photoinhibition. The resistance against photoinhibition was further increased by addition of extra NaHCO₃ up to about 5 mM. The normal oxygen content can be decreased profoundly without affecting the degree of photoinhibition; in contrast, even small changes from the normal bicarbonate content affected photoinhibition.At oxygen concentrations approximately below 25 M, added NaHCO₃ not only did not protect, but caused a more severe PS 2 inactivation. This was due to a blockage by added NaHCO₃ of the recovery from a reversible photoinhibited state.Furthermore, it is shown that if the bicarbonate ions bound to high-affinity sites in PS 2 were replaced by formate ions, the thylakoid membranes became less susceptible to photoinhibition under normal oxygen tension.Abbreviations chl chlorophyll - HEPES (N-[2-Hydroxyethyl]piperazine-N-[2-ethanesulfonic acid]) - PpBQ phenyl-p-benzoquinone - PS 2 Photosystem 2 - Q_A and Q_B primary and secondary quinone acceptors of Photosystem 2     

Growth and feeding of Fredericella sultana (bryozoa) in the outlet of a humic acid lake

Monthly observations on the bryozoa Fredericella sultana have been carried out in the outlet of a humic acid lake for more than two years. The growth of the colonies were rapid during algal bloom and in fall the colonies almost covered the free underside of nearly all stones on the bottom. In winter most of the colonies died out, but scattered individuals were also observed alive during this period. Statoblasts produced in summer were ‘hatching’ in March–April next year. F. sultana seems to feed on all particles that can pass through the mouth opening. A special study regarding this was made on the diatoms, by analysis of fecal pellets. It was found that young colonies of F. sultana filtrated most efficiently the smallest particles (<20 µm) while older individuals in addition were able to elevate the filtration of bigger particles (40–100 µm). The feeding takes place both by filtration by the cilia and by an active use of the tentacles themselves on the lophophore.     

Colostral Transfer in the Goat of Antibodies Against Corynebacterium Pseudotuberculosis and the Antibody Status of Kids During the First 10 Months of Life

Serum and colostrum samples from goats at parturition and serum samples from their kids at 3 days and at 4, 7, 10 and 12 weeks after birth were examined for the presence of antibodies to Corynebacterium pseudotuberculosis hemolysins. The hemolysis inhibition test (HIT) was used. High correlation was found between titre values of antihemolysins in serum and colostrum of goats at parturition (correlation coefficient r = 0.83; P < 0.01). Intermediate correlation was found between antihemolysin titre in colostrum of goats and in the sera of their kids 3 days old (r = 0.56; 0.01 < P < 0.05). Furthermore, titre values for 3 day-old kids showed high correlation with the antihemolysin titres when the kids aged 4 and 7 weeks (r = 0.76 and 0.85, respectively; P < 0.01). Antihemolysin titres decreased linearly in kids from 3 days to 10 weeks old. Calculated half life of antibodies was 12 days. Most of the kids had detectable antibodies up to the age of 5–6 weeks. None of the kids were seropositive at 2½ months of age. Serum samples collected monthly from a group of kids chosen at random, aged 7–10 months, contained antibodies to hemolysins in half of the animals at the first testing. At the age of 10 months 14 out of 15 kids were seropositive. Thus, most of the kids from this herd were exposed to G. pseudotuberculosis antigens during summer and autumn of their first year of life. Prophylactic measures against caseous lymphadenitis is briefly discussed.