Proteasome-dependent degradation of histone H1 subtypes is mediated by its C-terminal domain.

Histone H1 is involved in chromatin compaction and dynamics. In human cells, the H1 complement is formed by different amounts of somatic H1 subtypes, H1.0-H1.5 and H1X. The amount of each variant depends on the cell type, the cell cycle phase, and the time of development and can be altered in disease. However, the mechanisms regulating H1 protein levels have not been described. We have analyzed the contribution of the proteasome to the degradation of H1 subtypes in human cells using two different inhibitors: MG132 and bortezomib. H1 subtypes accumulate upon treatment with both drugs, indicating that the proteasome is involved in the regulation of H1 protein levels. Proteasome inhibition caused a global increase in cytoplasmatic H1, with slight changes in the composition of H1 bound to chromatin and chromatin accessibility and no alterations in the nucleosome repeat length. The analysis of the proteasome degradation pathway showed that H1 degradation is ubiquitin-independent. The whole protein and its C-terminal domain can be degraded directly by the 20S proteasome in vitro. Partial depletion of PA28γ revealed that this regulatory subunit contributes to H1 degradation within the cell. Our study shows that histone H1 protein levels are under tight regulation to prevent its accumulation in the nucleus. We revealed a new regulatory mechanism for histone H1 degradation, where the C-terminal disordered domain is responsible for its targeting and degradation by the 20S proteasome, a process enhanced by the regulatory subunit PA28γ.

Mycobacterium pinnipedii: transmission from South American sea lion (Otaria byronia) to Bactrian camel (Camelus bactrianus bactrianus) and Malayan tapirs (Tapirus indicus).

Tuberculosis infections caused by Mycobacterium (M.) pinnipedii in a South American sea lion, Bactrian camel, and Malayan tapirs kept in two zoological gardens spanning a time period of 5 years are reported. The zoos were linked by the transfer of one tapir. Conventional bacteriological and molecular methods were applied to detect the pathogen. Spoligotyping and MIRU/VNTR-typing performed to assess the genetic similarity revealed identical molecular characteristics of the isolates from all animals involved. Anti-tuberculosis antibodies were detected using ELISA and a recently developed serological rapid test. The study shows that: (i) using molecular methods, the assessment of the genetic relationship of infectious agents helps to confirm the routes of infection, and that (ii) immunological tests may help to detect tuberculosis infections ante mortem more reliably and early. This would prevent the transfer of tuberculosis by asymptomatic animals.

Simultaneous determination of fat-soluble vitamins and provitamins in milk by microcolumn liquid chromatography.

The fat-soluble vitamins A, D2, D3, E and K1, retinyl acetate, retinyl palmitate, tocopherol acetate, ergosterol and 7-dehydrocholesterol in milk were separated on a packed reversed-phase fused-silica microcolumn, and determined with UV detection. Conventional liquid chromatographic equipment was adapted for such purposes, providing a highly efficient and sensitive analytical system. The vitamins could be separated in gradient mode with detection limits comprised between 0.02 ng/ml for retinol and 2 ng/ml for vitamin E. All vitamins were separated in less than 17 min. Recovery studies showed good results for all solutes (89-107%) and the intra-day coefficients of variations ranged from 2 to 8%. Application of the proposed method to the quantification of fat-soluble vitamins in milk is reported.

Gas chromatographic analysis of total fatty acids in cider.

This paper reports the composition of total fatty acids in an apple beverage, cider. Fatty acids are present in the free or esterified form and contribute to both the flavor and foam properties of cider. Fatty acids were separated and identified as methyl esters by GC-MS, and 12 of these were subsequently determined by GC-FID. The major fatty acids found in cider were caproic, caprylic, capric, and palmitic acid, the saturated acids predominating over the unsaturated ones. The proposed method was applied to 59 ciders from three consecutive harvests (1996, 1997, and 1998), which were made by 19 cider-makers from the region of Asturias (Spain). Linear discriminant analysis of fatty acids in these samples allowed selection of palmitoleic, pentadecanoic, linoleic, myristic, and linolenic acid as the most predictive variables to differentiate ciders made from apples grown in the Asturias region (1997 harvest) and ciders made from apples grown outside this region (1996 and 1998 harvests).

Extraction-spectrophotometric determination of niobium with dibenzo-18-crown-6 and thiocyanate.

A method is described for the direct spectrophotometric determination of micro-amounts of niobium by extraction into a benzene solution of dibenzo-18-crown-6 (L) from 3M hydrochloric acid containing potassium thiocyanate. The molar absorptivity of the extracted complex is 3.85 +/- 0.03 x 10(4) 1.mole(-1).cm(-1) (relative standard deviation 0.8%). Co-ordinatively unsaturated complexes of the type [NbO(SCN)(3)](2)L and NbO(SCN)(3)L are extracted, along with ion-pairs, especially when small amounts of L are used for extraction. The ion-pair complex [NbOCl(2)(SCN)(3)][(LK)(2)] seems to be the main species formed in the organic phase.

Ion-pair extraction and fluorimetric determination of potassium with 18-crown-6 and eosin.

A highly sensitive and selective fluorimetric determination of potassium is proposed, based on solvent extraction of the ion-pair formed between a large anion and the cationic complex of K(+) with a crown ether. Sensitivity is achieved by selection of a highly fluorescent counter-ion of the fluorescein group (eosin). A linear working range from 0.01 to 1 ppm of potassium is obtained, which gives a higher sensitivity than any similar method for potassium determination. The relative standard deviation is 4-5%. Selectivity is achieved by matching the radius of the cavity of the 18-crown-6 to the ionic radius of potassium. The system used is exceptionally selective for extraction of potassium in the presence of alkali or alkaline-earth metal cations. The proposed method has been successfully applied to the determination of potassium in blood serum.

Extractive fluorimetric determination of ultratraces of lead with cryptand 2.2.2 and eosin.

A new speetrofluorimetric method for determination of ultratraces of lead is based on solvent extraction into chloroform of the ion-pair formed between the positively-charged cryptate of lead with cryptand 2.2.2 and the eosinate anion. The detection limit for lead is 1 ng ml , and the linear working range is from the detection limit to 250 ng ml . The relative standard deviation is 3.7% at the 100 ng ml level. The method is highly selective for the extraction and determination of lead in the presence of other cations, and has been tested for direct determination of lead contamination in soft drinks. Aggregation of the extracted ion-pair in the organic phase has been demonstrated in fundamental extraction studies.

Extractive fluorimetric determination of ultratraces of lead with 18-crown-6 and eosin.

A highly sensitive and selective spectrofluorimetric procedure for the determination of lead in the range 0.003-0.5 ppm, based on solvent extraction of the ion-pair formed between the eosinate anion and the cationic complex of Pb(2+) with 18-crown-6, has been developed. The relative standard deviation is 3.7% at the 0.1 ppm level. The metal :ligand: counter-ion molecular ratio in the ion-pair extracted is 1:1:1, but aggregation of the complex may occur in the organic phase. The system proposed is exceptionally selective for extraction of lead in the presence of other cations frequently associated with it. The proposed method has been tested in the determination of lead in tap water. The results show good agreement with those found by the more common extractive atomic-absorption method using ammonium tetramethylenedithiocarbamate.

Fluorimetric determination of ultratraces of lead by ion-pair extraction with cryptand 2.2.1 and eosin.

A spectrofluorimetric study of the extraction of lead into 1,2-dichloroethane, as an ion-pair formed between the cryptand 2.2.1-lead complex and the eosinate counter-ion is described. Optimum conditions for the extraction have been established and a new spectrofluorimetric determination of ultratraces of lead is proposed (detection limit 0.8 ng/ml; relative standard deviation 2.4% at the 60 ng/ml level). The metal:ligand:counter-ion molecular ratio in the extracted mononuclear ion-pair is 1:1:1. The equilibrium constants involved in the extraction have been estimated and refined by the Letagrop-DISTR program.

Ion-pair extraction and fluorimetric determination of cadmium with cryptand 2.2.1 and eosin.

A method is described for the direct spectrofluorimetric determination of ultratraces of cadmium by extraction into 1,2-dichloroethane of the ion-pair formed between the eosinate anion and the cationic complex of Cd(2+) with cryptand 2.2.1. The detection limit for cadmium is 0.5 ng/ml, and the linear working range is from the detection limit to 150 ng/ml. The relative standard deviation is 1.5% at the 100 ng/ml level. The equilibrium constant has been estimated and refined by the Letagrop-DISTR program. The proposed method has been tested in the determination of cadmium in high-purity zinc. The results show good agreement with those found by the more common ICP emission photometry and anodic stripping voltammetry methods.

Report and policy brief from the 4th Africa Conference on Social Aspects of HIV/AIDS Research: innovations in access to prevention, treatment and care in HIV/AIDS, Kisumu, Kenya, 29 April - 3 May 2007.

About 520 delegates from all over Africa and 21 countries attended the conference. This report and policy brief summarises the key findings and suggested policy options that emerged from rapporteur reports of conference proceedings including the following themes: (1) Orphans and vulnerable children, (2) Treatment, (3) Prevention, (4) Gender and male involvement, (5) Male circumcision, (6) People living with HIV/AIDS, (7) Food and nutrition, (8) Socioeconomics, and (9) Politics/policy. Two (11.8%) of the 17 OVC projects from the three countries were classified as best practice interventions. Of the 83 abstracts that were accepted at the conference, only 7 (8.4%) were dealing with antiretroviral therapy (ART). There has been tremendous effort by various organisations to provide information about prevention of HIV/AIDS. Information received by adolescents has been effective in increasing their knowledge, but without positive sexual behaviour change. The conference noted the contribution of gender discrimination and violence to the HIV epidemic and the different risks that men and women face in relation to the epidemic. Social scientists need to study the deep cultural meanings attached to male circumcision among different ethnic groups to be able to guide the debate on the latest biomedical findings on the protective effect of circumcision against HIV. Palliative care and support is crucial for coping among people living with HIV/AIDS (PLWHA) in order to deal with medical and psychological issues. Results from several countries have helped researchers to explore alternative ways of examining poverty in the context of HIV and AIDS. Policy frameworks which are likely to succeed in combating HIV/AIDS need to be updated to cover issues of access, testing, disclosure and stigma. In general, the conference was successful in identifying innovations in access to prevention, treatment and care in HIV/AIDS.

Sequential extraction--spectrofluorometric determination of lead and cadmium using cryptands.

A spectrofluorimetric method for the determination of ultratrace amounts of lead and cadmium is described based on the sequential extraction of the ternary ion-association complexes formed between the cation, a cryptand as the ligand and eosin as a counter ion. A linear working range from the detection limit (0.5 ng ml(-1) to 250 ng ml(-1) of lead and to 1 50 ng ml(-1) of cadmium was obtained. The relative standard deviation was 2-4%. The proposed method has been applied successfully to the determination of lead and cadmium in zinc metals and soft drinks.

Determination of acaricides in honey by liquid chromatography with ordinary, narrow-bore, and microbore columns.

Narrow-bore and microbore columns packed with octadecylsilane were used to compare their sensitivity and efficiency in the separation of coumaphos, fluvalinate, bromopropylate, and 4,4'-dibromobenzophenone from honey with those of ordinary columns. The best sensitivity for acaricides was accomplished by using a 150 mm × 0.32 mm i.d., 5 µm Spherisorb ODS-2 capillary column, methanol-water (90:10 v/v) as the mobile phase, and 5 µL/min as the flow rate. Detection limits for individual acaricides using a UV detection range from 0.40 to 0.74 µg/kg of honey were comparable to those obtained by gas chromatography using an electron capture detector. All acaricides were separated in <12 min. The coefficients of variations on real samples were <6.2%.

Simultaneous determination of vitamins D3, E and K1 and retinyl palmitate in cattle plasma by liquid chromatography with a narrow-bore column.

A reversed-phase high performance liquid chromatographic method is described for the simultaneous determination of vitamins D3, E and K1 and retinyl palmitate in plasma. Narrow-bore columns are recommended because this alternative provides a good separation efficiency, plus greater economy and sensitivity. Detection limits for individual vitamins range from 0.42 to 2.8 ng. All vitamins were separated in less than 9 min. Recovery studies showed good results for all solutes (88.8-100.3%) and the intra-day coefficients of variations ranged from 1.0 to 4.5%. This method permits the simple determination of fat-soluble vitamins using 1 ml of cattle heparinized plasma.

Mesoscale vertical motion and the size structure of phytoplankton in the ocean.

Phytoplankton size structure is acknowledged as a fundamental property determining energy flow through 'microbial' or 'herbivore' pathways. The balance between these two pathways determines the ability of the ecosystem to recycle carbon within the upper layer or to export it to the ocean interior. Small cells are usually characteristic of oligotrophic, stratified ocean waters, in which regenerated ammonium is the only available form of inorganic nitrogen and recycling dominates. Large cells seem to characterize phytoplankton in which inputs of nitrate enter the euphotic layer and exported production is higher. But the size structure of phytoplankton may depend more directly on hydrodynamical forces than on the source of available nitrogen. Here we present an empirical model that relates the magnitude of mesoscale vertical motion to the slope of the size-abundance spectrum of phytoplankton in a frontal ecosystem. Our model indicates that the relative proportion of large cells increases with the magnitude of the upward velocity. This suggests that mesoscale vertical motion-a ubiquitous feature of eddies and unstable fronts-controls directly the size structure of phytoplankton in the ocean.