Metaproteomic analysis of a winter to spring succession in coastal northwest Atlantic Ocean microbial plankton

In this study, we used comparative metaproteomics to investigate the metabolic activity of microbial plankton inhabiting a seasonally hypoxic basin in the Northwest Atlantic Ocean (Bedford Basin). From winter to spring, we observed a seasonal increase in high-affinity membrane transport proteins involved in scavenging of organic substrates; Rhodobacterales transporters were strongly associated with the spring phytoplankton bloom, whereas SAR11 transporters were abundant in the underlying waters. A diverse array of transporters for organic compounds were similar to the SAR324 clade, revealing an active heterotrophic lifestyle in coastal waters. Proteins involved in methanol oxidation (from the OM43 clade) and carbon monoxide (from a wide variety of bacteria) were identified throughout Bedford Basin. Metabolic niche partitioning between the SUP05 and ARCTIC96BD-19 clades, which together comprise the Gamma-proteobacterial sulfur oxidizers group was apparent. ARCTIC96BD-19 proteins involved in the transport of organic compounds indicated that in productive coastal waters this lineage tends toward a heterotrophic metabolism. In contrast, the identification of sulfur oxidation proteins from SUP05 indicated the use of reduced sulfur as an energy source in hypoxic bottom water. We identified an abundance of Marine Group I Thaumarchaeota proteins in the hypoxic deep layer, including proteins for nitrification and carbon fixation. No transporters for organic compounds were detected among the thaumarchaeal proteins, suggesting a reliance on autotrophic carbon assimilation. In summary, our analyses revealed the spatiotemporal structure of numerous metabolic activities in the coastal ocean that are central to carbon, nitrogen and sulfur cycling in the sea.     

Relative shortening and functional tethering of spinal cord in adolescent scoliosis – Result of asynchronous neuro-osseous growth, summary of an electronic focus group debate of the IBSE

There is no generally accepted scientific theory for the causes of adolescent idiopathic scoliosis (AIS). As part of its mission to widen understanding of scoliosis etiology, the International Federated Body on Scoliosis Etiology (IBSE) introduced the electronic focus group (EFG) as a means of increasing debate on knowledge of important topics. This has been designated as an on-line Delphi discussion. The Statement for this debate was written by Dr WCW Chu and colleagues who examine the spinal cord to vertebral growth interaction during adolescence in scoliosis. Using the multi-planar reconstruction technique of magnetic resonance imaging they investigated the relative length of spinal cord to vertebral column including ratios in 28 girls with AIS (mainly thoracic or double major curves) and 14 age-matched normal girls. Also evaluated were cerebellar tonsillar position, somatosensory evoked potentials (SSEPs), and clinical neurological examination. In severe AIS compared with normal controls, the vertebral column is significantly longer without detectable spinal cord lengthening. They speculate that anterior spinal column overgrowth relative to a normal length spinal cord exerts a stretching tethering force between the two ends, cranially and caudally leading to the initiation and progression of thoracic AIS. They support and develop the Roth-Porter concept of uncoupled neuro-osseous growth in the pathogenesis of AIS which now they prefer to term ' asynchronous neuro-osseous growth'. Morphological evidence about the curve apex suggests that the spinal cord is also affected, and a 'double pathology' is suggested. AIS is viewed as a disorder with a wide spectrum and a common neuroanatomical abnormality namely, a spinal cord of normal length but short relative to an abnormally lengthened anterior vertebral column. Neuroanatomical changes and/or abnormal neural function may be expressed only in severe cases. This asynchronous neuro-osseous growth concept is regarded as one component of a larger concept. The other component relates to the brain and cranium of AIS subjects because abnormalities have been found in brain (infratentorial and supratentorial) and skull (vault and base). The possible relevance of systemic melatonin-signaling pathway dysfunction, platelet calmodulin levels and putative vertebral vascular biology to the asynchronous neuro-osseous growth concept is discussed. A biomechanical model to test the spinal component of the concept is in hand. There is no published research on the biomechanical properties of the spinal cord for scoliosis specimens. Such research on normal spinal cords includes movements (kinematics), stress-strain responses to uniaxial loading, and anterior forces created by the stretched cord in forward flexion that may alter sagittal spinal shape during adolescent growth. The asynchronous neuro-osseous growth concept for the spine evokes controversy. Dr Chu and colleagues respond to five other concepts of pathogenesis for AIS and suggest that relative anterior spinal overgrowth and biomechanical growth modulation may also contribute to AIS pathogenesis.     

Partial <Emphasis Type="Italic">AZFc</Emphasis> deletions and duplications: clinical correlates in the Italian population

The role of partial AZFc deletions of the Y chromosome in spermatogenic impairment is currently debated. Recently, it was also reported that duplications of the same region are associated with oligozoospermia in Han-Chinese men. The aims of this study were (1) to evaluate the clinical significance of partial AZFc deletions in a large study population and (2) to define if partial AZFc duplications are a risk factor for spermatogenic failure also in a Caucasian population such as the Italian. We screened 556 infertile patients and 487 normozoospermic controls for partial AZFc deletions with a combined method based on STS+/− followed by CDY1-DAZ gene dosage and copy analysis. For the second aim, we performed CDY1-DAZ gene dosage in 229 infertile patients and 263 normozoospermic controls. The frequency of gr/gr deletions in patients was significantly different from the controls (3.2 vs. 0.4%, respectively; P < 0.001), with an OR = 7.9 (95% CI 1.8–33.8). b2/b3 deletions were rare in both groups (0.5% in patients, 0.2% in controls). Concerning gr/gr duplications, we observed no significant differences in their frequency between cases (2.6%) and controls (3.8%). This is the largest study population in the literature in which all potential methodological and selection biases were carefully avoided to detect the clinical significance of partial AZFc deletions and duplications. Our study provides strong evidence that gr/gr deletion is a risk factor for impaired spermatogenesis, whereas we did not detect a significant effect of b2/b3 deletions and partial AZFc duplications on spermatogenesis in this Caucasian ethnic group. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users.     

Quantum efficiency distributions of photo-induced side-pathway donor oxidation at cryogenic temperature in photosystem II

We monitored illuminated-minus-dark absorption difference spectra in the range of 450-1100 nm induced by continuous illumination at 8 K of photosystem II (PSII) core complexes from Thermosynechococcus elongatus. The photo-induced oxidation of the side-path donors Cytb(559), beta-carotene and chlorophyll Z, as well as the concomitant stable (t(1/2) > 1 s) reduction of the first plastoquinone electron acceptor, Q(A) (monitored by the well-known 'C550' shift), were quantified as a function of the absorbed photons per PSII. The Q(A) photo-induced reduction data can be described by three distinct quantum efficiency distributions: (i) a very high efficiency of approximately 0.5-1, (ii) a middle efficiency with a very large range of approximately 0.014-0.2, and (iii) a low efficiency of approximately 0.002. Each of the observed side-path donors exhibited similar quantum efficiency distributions, which supports a branched pathway model for side-path oxidation where beta-carotene is the immediate electron donor to the photo-oxidized chlorophyll (P680(+)). The yields of the observed side-path donors account quantitatively for the wide middle efficiency range of photo-induced Q(A) reduction, but not for the PSII fractions that exhibit the highest and lowest efficiencies. The high-efficiency component may be due to Tyr(Z) oxidation. A donor that does not exhibit an identified absorption in the visible-near-IR region is mainly responsible for the lowest efficiency component.     

Photobactericidal plastic films based on cellulose esterified by chloroacetate and a cationic porphyrin

The synthesis and characterisation of pyridinium porphyrinic chloroacetyl cellulose ester chlorides, where photosensitizing agents are covalently bounded to the polymeric chain, is presented in this paper. First, cellulose was homogenously converted into chloroacetate cellulose ester in DMAc/LiCl solvent by using chloroacetyl chloride. The complete substitution of cellulose was achieved using 7equiv of chloroacetyl chloride for a 2h reaction at room temperature. The absence of base did not prove detrimental to reaction. The grafting of monopyridyltritolylporphyrin onto chloroacetate cellulose ester was then realised by alkylation of the photosensitizer in DMF. These new plastic films were found to be thermostable up to 55 degrees C; higher temperatures led to progressive deacetylation. First results of their photobactericidal activity against Staphylococcus aureus and Escherichia coli strains are very encouraging. Such materials could find applications in medical environments as an alternative to overcome the rampant bacterial multiresistance to classical antibiotics.     

A subgenomic segment of Theiler's murine encephalomyelitis virus RNA causes demyelination

The DA strain of Theiler's murine encephalomyelitis virus (TMEV) causes a persistent central nervous system (CNS) infection of mice with a restricted virus gene expression and induces an inflammatory demyelinating disease that is thought to be immune mediated and a model of multiple sclerosis (MS). The relative contribution of virus vis-à-vis the immune system in the pathogenesis of DA-induced white matter disease remains unclear, as is also true in MS. To clarify the pathogenesis of DA-induced demyelination, we used Cre/loxP technology to generate a transgenic mouse that has tamoxifen (Tm)-inducible expression of a subgenomic segment of DA RNA in oligodendrocytes and Schwann cells. Tm-treated young transgenic mice developed progressive weakness leading to death, with abnormalities of oligodendrocytes and Schwann cells and demyelination, but without inflammation, demonstrating that DA virus can play a direct pathogenic role in demyelination. Tm treatment of mice at a later age resulted in milder disease, with evidence of peripheral nerve remyelination and focal fur depigmentation; surviving weak mice had persistent expression of the recombined transgene in the CNS, suggesting that the DA subgenomic segment can cause cellular dysfunction but not death, possibly similar to the situation seen during DA virus persistence. These studies demonstrate that DA RNA or a DA protein(s) is toxic to myelin-synthesizing cells. This Cre/loxP transgenic system allows for spatially and temporally controlled expression of the viral transgene and is valuable for clarifying nonimmune (and immune) mechanisms of demyelination induced by TMEV as well as other viruses.     

Y-chromosome lineages trace diffusion of people and languages in southwestern Asia

The origins and dispersal of farming and pastoral nomadism in southwestern Asia are complex, and there is controversy about whether they were associated with cultural transmission or demic diffusion. In addition, the spread of these technological innovations has been associated with the dispersal of Dravidian and Indo-Iranian languages in southwestern Asia. Here we present genetic evidence for the occurrence of two major population movements, supporting a model of demic diffusion of early farmers from southwestern Iran-and of pastoral nomads from western and central Asia-into India, associated with Dravidian and Indo-European-language dispersals, respectively.