New insights on ChlD1 function in Photosystem II from site-directed mutants of D1/T179 in Thermosynechococcus elongatus

The monomeric chlorophyll, Chl_D1, which is located between the P_D1P_D2 chlorophyll pair and the pheophytin, Pheo_D1, is the longest wavelength chlorophyll in the heart of Photosystem II and is thought to be the primary electron donor. Its central Mg²⁺ is liganded to a water molecule that is H-bonded to D1/T179. Here, two site-directed mutants, D1/T179H and D1/T179V, were made in the thermophilic cyanobacterium, Thermosynechococcus elongatus, and characterized by a range of biophysical techniques. The Mn₄CaO₅ cluster in the water-splitting site is fully active in both mutants. Changes in thermoluminescence indicate that i) radiative recombination occurs via the repopulation of *Chl_D1 itself; ii) non-radiative charge recombination reactions appeared to be faster in the T179H-PSII; and iii) the properties of P_D1P_D2 were unaffected by this mutation, and consequently iv) the immediate precursor state of the radiative excited state is the Chl_D1⁺Pheo_D1^? radical pair. Chlorophyll bleaching due to high intensity illumination correlated with the amount of ¹O₂ generated. Comparison of the bleaching spectra with the electrochromic shifts attributed to Chl_D1 upon Q_A^? formation, indicates that in the T179H-PSII and in the WT*3-PSII, the Chl_D1 itself is the chlorophyll that is first damaged by ¹O₂, whereas in the T179V-PSII a more red chlorophyll is damaged, the identity of which is discussed. Thus, Chl_D1 appears to be one of the primary damage site in recombination-mediated photoinhibition. Finally, changes in the absorption of Chl_D1 very likely contribute to the well-known electrochromic shifts observed at ~430?nm during the S-state cycle.     

Proliferation and differentiation of ductular progenitor cells and littoral cells during the regeneration of the rat liver to CCl4/2-AAF injury

Restoration of centrolobular injury induced by carbon tetrachloride (CCl4), when hepatocyte proliferation is inhibited by treatment with N-2-acetylaminofluorene (AAF), is accomplished by proliferation of ductular progenitor cells, that arise intraportally and extend into the liver lobule. This pattern contrasts to the restitutive proliferation of hepatocytes when AAF is not administered, and the proliferation of non-ductular periportal oval cells follows periportal necrosis induced by allyl alcohol. The expanding ducts stain for alphafetoprotein (AFP), OV-6, pan-cytokeratin (CKPan), and laminin. The neoductular proliferation is accompanied by fibronectin-positive Kupffer cells and desmin-positive stellate (Ito) cells, which may play critical roles not only in controlling proliferation and differentiation of ductular progenitor cells, but also in reestablishing hepatic cord structure. When AAF is discontinued 7 days after injury, clusters of small hepatocytes appear next to the neoductules. Some of these small hepatocytes, as well as some larger hepatocytes adjacent to the ducts, stain for AFP and for carbamoylphosphate synthetase I (CPS-I), suggesting that the ductular progenitor cells may differentiate into hepatocytes when AAF is withdrawn. The restitutive process is facilitated by clearing of the central necrotic zone by infiltrating macrophages and co-migration of mature hepatocytes, with Kupffer cells and stellate cells, into the necrotic zone.     

The hepatocyte: heterogeneity and plasticity of liver cells

The heterogeneity of the proliferative response of the liver to injury and during hepatocarcinogenesis implicates at least four levels of cells in the hepatic lineage which respond: the mature unipolar hepatocyte, the unipolar duct cell, a bipolar ductular progenitor cell, and a multipotent periductular liver progenitor cell of presumed extra-hepatic (bone marrow) origin (1). The original concept of "embryonal rests" as the cells or origin of cancer in adult organs (2) may be correct in the sense that progenitor cells in adult tissues that give rise to cancers may derive from circulating pluripotent stem cells.     

Winter blooming ofArtemisia. A 2-year survey in murcia (Spain)

This paper presents a 2-year survey ofArtemisia airborne pollen concentrations in Murcia. An importantArtemisia blooming taking place in winter is confirmed in Murcia (SE Spain). This phenomenon could explain the incidence of winter pollinosis in Murcia. On the other hand, for the first time, three consecutive pollen seasons ofArtemisia, corresponding to three different species (A. campestris, A. herba-alba andA. barrelieri) have been noted. Mathematical analyses show the relations between pollen concentrations ofArtemisia in summer and autumn, and precipitation occurring 6–8 weeks before. Blooming outsets seem to be related to cumulative percentage of isolation from 1 March. Meteorological factors do not seem to influence pollen concentration in any significant way once pollination has begun.     

The Utility of an Online Convenience Panel for Reaching Rare and Dispersed Populations

Gaps in data collection systems, as well as challenges associated with gathering data from rare and dispersed populations, render current health surveillance systems inadequate to identify and monitor efforts to reduce health disparities. Using sexual and gender minorities we investigated the utility of using a large nonprobability online panel to conduct rapid population assessments of such populations using brief surveys. Surveys of the Google Android Panel (four assessing sexual orientation and one assessing gender identity and sex assigned at birth) were conducted resulting in invitation of 53,739 application users (37,505 of whom viewed the invitation) to generate a total of 34,759 who completed screening questions indicating their sexual orientation, or gender identity and sex at birth. Where possible we make comparisons to similar data from two population-based surveys (NHIS and NESARC). We found that 99.4% to 100.0% of respondents across our Google Android panel samples completed the screening questions and 97.8% to 99.2% of those that consented to participate in our surveys indicated they were “OK” with the content of surveys that assessed sexual orientation and sex/gender. In our Google Android panel samples there was a higher percentage of sexual minority respondents than in either NHIS or NESARC with 7.4% of men and 12.4% of women reporting gay, lesbian or bisexual identities. The proportion sexual minority was 2.8 to 5.6 times higher in the Google Android panel samples than was found in the 2012 NHIS sample, for men and women, respectively. The percentage of “transgender” identified individuals in the Google sample was 0.7%, which is similar to 0.5% transgender identified through the Massachusetts BRFSS, and using a transgender status item we found that 2.0% of the overall sample fit could be classified as transgender. The Google samples sometimes more closely approximated national averages for ethnicity and race than NHIS.     

Shedding of dipeptidyl peptidase 4 is mediated by metalloproteases and up-regulated by hypoxia in human adipocytes and smooth muscle cells

Dipeptidyl peptidase 4 is an important drug target for diabetes and a novel adipokine. However, it is unknown how soluble DPP4 (sDPP4) is cleaved from the cell membrane and released into the circulation. We show here that MMP1, MMP2 and MMP14 are involved in DPP4 shedding from human vascular smooth muscle cells (SMC) and MMP9 from adipocytes. Hypoxia increased DPP4 shedding from SMC which is associated with increased mRNA expression of MMP1. Our data suggest that constitutive as well as hypoxia-induced DPP4 shedding occurs due to a complex interplay between different MMPs in cell type-specific manner.     

A new view on dam lines in Polish Arabian horses based on mtDNA analysis

Polish Arabian horses are one of the oldest and the most important Arab populations in the world. The Polish Arabian Stud Book and the Genealogical Charts by Skorkowski are the main sources of information on the ancestors of Polish Arabs. Both publications were viewed as credible sources of information until the 1990s when the data regarding one of the dam lines was questioned. The aim of the current study was to check the accuracy of the pedigree data of Polish dam lines using mtDNA analysis. The analyses of a 458 bp mtDNA D-loop fragment from representatives of 15 Polish Arabian dam lines revealed 14 distinct haplotypes. The results were inconsistent with pedigree data in the case of two lines. A detailed analysis of the historical sources was performed to explain these discrepancies. Our study revealed that representatives of different lines shared the same haplotypes. We also noted a genetic identity between some lines founded by Polish mares of unknown origin and lines established by desert-bred mares.     

Strength, flexibility, and balance characteristics of highly proficient golfers

Despite the emergence of golf-specific training programs and training aids, relatively little research has been conducted examining the physical characteristics that are important to golf performance. We studied the strength, flexibility, and balance characteristics of golfers across 3 proficiency levels based on handicap index (HCP) (<0, 1-9, and 10-20) to determine the physical characteristics unique to highly proficient golfers. A total of 257 (age: 45.5 +/- 12.8 years, height: 180.6 +/- 6.5 cm, weight: 87.9 +/- 12.6 kg) healthy, male golfers participated in the study. Testing included an assessment of strength (torso, shoulder, and hip), flexibility (torso, shoulder, and hip), and single-leg balance. Golfers in the highest proficiency group (HCP < 0) had significantly (p < 0.05) greater hip strength, torso strength, shoulder strength, shoulder flexibility, hip flexibility, torso flexibility, and balance (eyes open) than golfers in the lowest proficiency group (HCP 10-20). The results of this study demonstrate that better golfers possess unique physical characteristics that are important to greater proficiency. These characteristics have also been demonstrated to be modifiable through golf-specific training programs.