A tale of time and depth: intralacustrine radiation in endemic Gammarus species flock from the ancient Lake Ohrid

Tentatively dated, the Plio‐/Pleistocene origin of the ancient Lake Ohrid on the Balkan Peninsula makes it the oldest ancient lake in Europe. Given the surface area of the lake and the adjusted endemicity rate, it may be also defined as the most diverse of all the ancient lakes in the world. From all the animal groups endemic to this lake, gammarids are amongst the most scarcely known in terms of their diversity and phylogenetic relationships. Partial DNA sequences of two mitochondrial genes, cytochrome oxidase subunit I (cox1) and 16S ribosomal RNA (16S rRNA) of eight known endemic Gammarus species from the Lake Ohrid valley were analysed. Phylogenetic analyses showed that endemic Gammarus species comprise an ancient species flock, with Gammarus sketi from the feeder springs being their sister taxon outside the lake. Amongst the species inhabiting the lake, Gammarus solidus and Gammarus salemaai are morphologically and molecularly well defined. By contrast, Gammarus ochridensis, Gammarus parechiniformis, Gammarus lychnidensis, and Gammarus stankokaramani revealed high discrepancy between morphological and genetic data. None of these morphospecies form a monophyletic clade and a significant degree of apparent gene flow occurs between them. This could be caused by incomplete lineage sorting and/or hybridization events. Two novel mtDNA lineages were found within the lake, possibly constituting two new species (Gammarus sp. 1 and Gammarus sp. 2). Molecular clock analysis showed that the split between G. sketi and the Gammarus species flock from the lake occurred approximately 5–7 Mya, whereas within the flock there were at least two intralacustrine radiations: one estimated at 2–3 Mya and the second at less than 1 Mya. The first one could be associated with the origin of the lake and the second with the lake water‐level fluctuations during Pleistocene. © 2013 The Linnean Society of London     

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.     

Phylogenetic utility of the nuclear gene arginine decarboxylase: an example from Brassicaceae

Arginine decarboxylase (ADC) is an important enzyme in the production of putrescine and polyamines in plants. It is encoded by a single or low-copy nuclear gene that lacks introns in sequences studied to date. The rate of Adc amino acid sequence evolution is similar to that of ndhF for the angiosperm family studied. Highly conserved regions provide several target sites for PCR priming and sequencing and aid in nucleotide and amino acid sequence alignment across a range of taxonomic levels, while a variable region provides an increased number of potentially informative characters relative to ndhF for the taxa surveyed. The utility of the Adc gene in plant molecular systematic studies is demonstrated by analysis of its partial nucleotide sequences obtained from 13 representatives of Brassicaceae and 3 outgroup taxa, 2 from the mustard oil clade (order Capparales) and 1 from the related order Malvales. Two copies of the Adc gene, Adc1 and Adc2, are found in all members of the Brassicaceae studied to data except the basal genus Aethionema. The resulting Adc gene tree provides robust phylogenetic data regarding relationships within the complex mustard family, as well as independent support for proposed tribal realignments based on other molecular data sets such as those from chloroplast DNA.      

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.