Colonization of subsurface microbial observatories deployed in young ocean crust

Oceanic crust comprises the largest hydrogeologic reservoir on Earth, containing fluids in thermodynamic disequilibrium with the basaltic crust. Little is known about microbial ecosystems that inhabit this vast realm and exploit chemically favorable conditions for metabolic activities. Crustal samples recovered from ocean drilling operations are often compromised for microbiological assays, hampering efforts to resolve the extent and functioning of a subsurface biosphere. We report results from the first in situ experimental observatory systems that have been used to study subseafloor life. Experiments deployed for 4 years in young (3.5 Ma) basaltic crust on the eastern flank of the Juan de Fuca Ridge record a dynamic, post-drilling response of crustal microbial ecosystems to changing physical and chemical conditions. Twisted stalks exhibiting a biogenic iron oxyhydroxide signature coated the surface of mineral substrates in the observatories; these are biosignatures indicating colonization by iron oxidizing bacteria during an initial phase of cool, oxic, iron-rich conditions following observatory installation. Following thermal and chemical recovery to warmer, reducing conditions, the in situ microbial structure in the observatory shifted, becoming representative of natural conditions in regional crustal fluids. Firmicutes, metabolic potential of which is unknown but may involve N or S cycling, dominated the post-rebound bacterial community. The archaeal community exhibited an extremely low diversity. Our experiment documented in situ conditions within a natural hydrological system that can pervade over millennia, exemplifying the power of observatory experiments for exploring the subsurface basaltic biosphere, the largest but most poorly understood biotope on Earth.     

Quick and clean cloning: a ligation-independent cloning strategy for selective cloning of specific PCR products from non-specific mixes

We have developed an efficient strategy for cloning of PCR products that contain an unknown region flanked by a known sequence. As with ligation-independent cloning, the strategy is based on homology between sequences present in both the vector and the insert. However, in contrast to ligation-independent cloning, the cloning vector has homology with only one of the two primers used for amplification of the insert. The other side of the linearized cloning vector has homology with a sequence present in the insert, but nested and non-overlapping with the gene-specific primer used for amplification. Since only specific products contain this sequence, but none of the non-specific products, only specific products can be cloned. Cloning is performed using a one-step reaction that only requires incubation for 10 minutes at room temperature in the presence of T4 DNA polymerase to generate single-stranded extensions at the ends of the vector and insert. The reaction mix is then directly transformed into E. coli where the annealed vector-insert complex is repaired and ligated. We have tested this method, which we call quick and clean cloning (QC cloning), for cloning of the variable regions of immunoglobulins expressed in non-Hodgkin lymphoma tumor samples. This method can also be applied to identify the flanking sequence of DNA elements such as T-DNA or transposon insertions, or be used for cloning of any PCR product with high specificity.     

Regulation of phosphatidylserine exposure in red blood cells

The exposure of phosphatidylserine (PS) on the outer membrane leaflet of red blood cells (RBCs) serves as a signal for eryptosis, a mechanism for the RBC clearance from blood circulation. The process of PS exposure was investigated as function of the intracellular Ca(2+) content and the activation of PKCα in human and sheep RBCs. Cells were treated with lysophosphatidic acid (LPA), 4-bromo-A23187, or phorbol-12 myristate-13 acetate (PMA) and analysed by flow cytometry, single cell fluorescence video imaging, or confocal microscopy. For human RBCs, no clear correlation existed between the number of cells with an elevated Ca(2+) content and PS exposure. Results are explained by three different mechanisms responsible for the PS exposure in human RBCs: (i) Ca(2+)-stimulated scramblase activation (and flippase inhibition) by LPA, 4-bromo-A23187, and PMA; (ii) PKC activation by LPA and PMA; and (iii) enhanced lipid flop caused by LPA. In sheep RBCs, only the latter mechanism occurs suggesting absence of scramblase activity.     

Interaction of influenza A virus matrix protein with RACK1 is required for virus release

The mechanism of budding of influenza A virus revealed important deviation from the consensus mechanism of budding of retroviruses and of a growing number of negative-strand RNA viruses. This study is focused on the role of the influenza A virus matrix protein M1 in virus release. We found that a mutation of the proline residue at position 16 of the matrix protein induces inhibition of virus detachment from cells. Depletion of the M1-binding protein RACK1 also impairs virus release and RACK1 binding requires the proline residue at position 16 of M1. The impaired M1-RACK1 interaction does not affect the plasma membrane binding of M1; in contrast, RACK1 is recruited to detergent-resistant membranes in a M1-proline-16-dependent manner. The proline-16 mutation in M1 and depletion of RACK1 impairs the pinching-off of the budding virus particles. These findings reveal the active role of the viral matrix protein in the release of influenza A virus particles that involves a cross-talk with a RACK1-mediated pathway.     

Nemitin, a novel Map8/Map1s interacting protein with Wd40 repeats

In neurons, a highly regulated microtubule cytoskeleton is essential for many cellular functions. These include axonal transport, regional specialization and synaptic function. Given the critical roles of microtubule-associated proteins (MAPs) in maintaining and regulating microtubule stability and dynamics, we sought to understand how this regulation is achieved. Here, we identify a novel LisH/WD40 repeat protein, tentatively named nemitin (neuronal enriched MAP interacting protein), as a potential regulator of MAP8-associated microtubule function. Based on expression at both the mRNA and protein levels, nemitin is enriched in the nervous system. Its protein expression is detected as early as embryonic day 11 and continues through adulthood. Interestingly, when expressed in non-neuronal cells, nemitin displays a diffuse pattern with puncta, although at the ultrastructural level it localizes along the microtubule network in vivo in sciatic nerves. These results suggest that the association of nemitin to microtubules may require an intermediary protein. Indeed, co-expression of nemitin with microtubule-associated protein 8 (MAP8) results in nemitin losing its diffuse pattern, instead decorating microtubules uniformly along with MAP8. Together, these results imply that nemitin may play an important role in regulating the neuronal cytoskeleton through an interaction with MAP8.     

A bovine model of respiratory Chlamydia psittaci infection: challenge dose titration

This study aimed to establish and evaluate a bovine respiratory model of experimentally induced acute C. psittaci infection. Calves are natural hosts and pathogenesis may resemble the situation in humans. Intrabronchial inoculation of C. psittaci strain DC15 was performed in calves aged 2-3 months via bronchoscope at four different challenge doses from 10(6) to 10(9) inclusion-forming units (ifu) per animal. Control groups received either UV-inactivated C. psittaci or cell culture medium. While 10(6) ifu/calf resulted in a mild respiratory infection only, the doses of 10(7) and 10(8) induced fever, tachypnea, dry cough, and tachycardia that became apparent 2-3 days post inoculation (dpi) and lasted for about one week. In calves exposed to 10(9) ifu C. psittaci, the respiratory disease was accompanied by severe systemic illness (apathy, tremor, markedly reduced appetite). At the time point of most pronounced clinical signs (3 dpi) the extent of lung lesions was below 10% of pulmonary tissue in calves inoculated with 10(6) and 10(7) ifu, about 15% in calves inoculated with 10(8) and more than 30% in calves inoculated with 10(9) ifu C. psittaci. Beside clinical signs and pathologic lesions, the bacterial load of lung tissue and markers of pulmonary inflammation (i.e., cell counts, concentration of proteins and eicosanoids in broncho-alveolar lavage fluid) were positively associated with ifu of viable C. psittaci. While any effect of endotoxin has been ruled out, all effects could be attributed to infection by the replicating bacteria. In conclusion, the calf represents a suitable model of respiratory chlamydial infection. Dose titration revealed that both clinically latent and clinically manifest infection can be reproduced experimentally by either 10(6) or 10(8) ifu/calf of C. psittaci DC15 while doses above 10(8) ifu C. psittaci cannot be recommended for further studies for ethical reasons. This defined model of different clinical expressions of chlamydial infection allows studying host-pathogen interactions.     

Patient Satisfaction with HIV/AIDS Care and Treatment in the Decentralization of Services Delivery in Vietnam

Objective

We evaluated the patient satisfaction with HIV/AIDS care and treatment and its determinants across levels of health service administration in Vietnam.

Methods

We interviewed 1016 patients at 7 hospitals and health centers in three epicenters, including Hanoi, Hai Phong, and Ho Chi Minh City. The Satisfaction with HIV/AIDS Treatment Interview Scale (SATIS) was developed, and 3 dimensions were constructed using factor analysis, namely “Quality and Convenience”; “Availability and Responsiveness”; and “Competence of health care workers”.

Results

In a band score of (0; 10), the mean scores of all domains were large; it was the highest in “Competence of health workers” (9.34±0.84), and the lowest in “Quality and Convenience” (9.03±1.04). The percentages of respondents completely satisfied with overall service quality and treatment outcomes were 42.4% and 18.8%, respectively. In multivariate analysis, factors related to higher satisfaction included female sex, older age, and living with spouses or partners. Meanwhile, lower satisfaction was found among patients who were attending provincial and district clinics; in the richest group; had higher CD4 count; and drug users.

Conclusion

This study highlights the importance of improving the quality of HIV/AIDS services at the provincial and district clinics. Potential strategies include capacity building for health workers, integrative service delivery, engagements of family members in treatment supports, and additional attention and comprehensive care for drug users with HIV/AIDS.     

Nanomechanics and sodium permeability of endothelial surface layer modulated by hawthorn extract WS 1442

The endothelial glycocalyx (eGC) plays a pivotal role in the physiology of the vasculature. By binding plasma proteins, the eGC forms the endothelial surface layer (ESL) which acts as an interface between bloodstream and endothelial cell surface. The functions of the eGC include mechanosensing of blood flow induced shear stress and thus flow dependent vasodilation. There are indications that levels of plasma sodium concentrations in the upper range of normal and beyond impair flow dependent regulation of blood pressure and may therefore increase the risk for hypertension. Substances, therefore, that prevent sodium induced endothelial dysfunction may be attractive for the treatment of cardiovascular disease. By means of combined atomic force-epifluorescence microscopy we studied the impact of the hawthorn (Crataegus spp.) extract WS 1442, a herbal therapeutic with unknown mechanism of action, on the mechanics of the ESL of ex vivo murine aortae. Furthermore, we measured the impact of WS 1442 on the sodium permeability of endothelial EA.hy 926 cell monolayer. The data show that (i) the ESL contributes by about 11% to the total endothelial barrier resistance for sodium and (ii) WS 1442 strengthens the ESL resistance for sodium up to about 45%. This mechanism may explain some of the vasoprotective actions of this herbal therapeutic.