Can molecular cell biology explain chromosome motions?

<p>Abstract</p> <p>Background</p> <p>Mitotic chromosome motions have recently been correlated with electrostatic forces, but a lingering "molecular cell biology" paradigm persists, proposing binding and release proteins or molecular geometries for force generation.</p> <p>Results</p> <p>Pole-facing kinetochore plates manifest positive charges and interact with negatively charged microtubule ends providing the motive force for poleward chromosome motions by classical electrostatics. This conceptual scheme explains dynamic tracking/coupling of kinetochores to microtubules and the simultaneous depolymerization of kinetochore microtubules as poleward force is generated.</p> <p>Conclusion</p> <p>We question here why cells would prefer complex molecular mechanisms to move chromosomes when direct electrostatic interactions between known bound charge distributions can accomplish the same task much more simply.</p

Divergence of AMP Deaminase in the Ice Worm Mesenchytraeus solifugus (Annelida, Clitellata, Enchytraeidae)

Glacier ice worms, Mesenchytraeus solifugus and related species, are the largest glacially obligate metazoans. As one component of cold temperature adaptation, ice worms maintain atypically high energy levels in an apparent mechanism to offset cold temperature-induced lethargy and death. To explore this observation at a mechanistic level, we considered the putative contribution of 5′ adenosine monophosphate deaminase (AMPD), a key regulator of energy metabolism in eukaryotes. We cloned cDNAs encoding ice worm AMPD, generating a fragment encoding 543 amino acids that included a short N-terminal region and complete C-terminal catalytic domain. The predicted ice worm AMPD amino acid sequence displayed conservation with homologues from other mesophilic eukaryotes with notable exceptions. In particular, an ice worm-specific K188E substitution proximal to the AMP binding site likely alters the architecture of the active site and negatively affects the enzyme's activity. Paradoxically, this would contribute to elevated intracellular ATP levels, which appears to be a signature of cold adapted taxa

Factors affecting velvet antler weights in free-ranging reindeer in Alaska

Free-ranging reindeer on the Seward Peninsula in western Alaska are rounded up from late May to early July and antlers are removed. We used data collected from 1987 to 1997 to determine how velvet antler weights of males and females varied with age, year, reproductive status, Julian date, and body weight. Male antler weights increased with age up to age five years, and were lower in castrates than in bulls. There was a significant positive relationship between body weight and antler weight in both sexes. Female antler weights increased with age until at least age nine. Lactating females had lower antler weights than non-lactating females, but this effect is better explained by differences in body weight. Antler weight of individual reindeer at age two years was better predicted by their antler weights as yearlings than their body weight as yearlings

Lactation in yearling Alaskan reindeer: Implications for growth, reproduction, and survival

Unlike most Rangifer herds, free-ranging female reindeer {Rangifer tarandus) on the Seward Peninsula, Alaska frequently give birth as yearlings (12 months). In other reindeer herds this early reproduction has led to negative effects such as decreased future weight gain and reproduction. We analyzed reindeer data collected on the Seward Peninsula between 1987 and 1997 to determine what effect lactating as yearlings had on future weight gain, reproductive rates, and survival. Reindeer were rounded up during June and early July. Individual ear tag numbers were recorded, females were visually inspected for the presence of a distended udder, and some animals were weighed. Females with distended udders as yearlings had subsequent recapture rates, survival rates, weight gain, and future reproductive success comparable to females that did not have distended udders as yearlings. These findings suggest that the beneficial effects of increased calf weight gain outweigh potential negative effects of early reproduction in these reindeer. This may be due to high quality range leading to heavy calves and the ability of females to maintain body reserves during lactation

A Glutamine-Rich Factor Affects Stem Cell Genesis in Leech

Leech embryogenesis is a model for investigating cellular and molecular processes of development. Due to the unusually large size of embryonic stem cells (teloblasts: 50–300 μm) in the glossiphoniid leech, Theromyzon tessulatum, and the presence of identifiable stem cell precursors (proteloblasts), we previously isolated a group of genes upregulated upon stem cell birth. In the current study, we show that one of these genes, designated Theromyzon proliferation (Tpr), is required for normal stem cell genesis; specifically, transient Tpr knockdown experiments conducted with antisense oligonucleotides and monitored by semiquantitative RT-PCR, caused abnormal proteloblast proliferation leading to embryonic death, but did not overtly affect neuroectodermal or mesodermal stem cell development once these cells were born. Tpr encodes a large glutamine-rich (∼34%) domain that shares compositional similarity with strong transcriptional enhancers many of which have been linked with trinucleotide repeat disorders (e.g., Huntington's)

All-sky Galactic radiation at 45 MHz and spectral index between 45 and 408 MHz

Aims: We study the Galactic large-scale synchrotron emission by generating a reliable all-sky spectral index map and temperature map at 45 MHz. Methods: We use our observations, the published all-sky map at 408 MHz, and a bibliographical compilation to produce a map corrected for zero-level offset and extragalactic contribution. Results: We present full sky maps of the Galactic emission at 45 MHz and the Galactic spectral index between 45 and 408 MHz with an angular resolution of 5\degs. The spectral index varies between 2.1 and 2.7, reaching values below 2.5 at low latitude because of thermal free-free absorption and its maximum in the zone next to the Northern Spur.Comment: A&A accepte

Exploratory investigation of drivers of attainment in ethnic minority adult learners

There is evidence that ethnic minority learners in further education in England either under-achieve or are under-represented because they face various inhibitors connected to their ethnicity. Motivators may be in place, however, which increase attainment specifically for some ethnic groups. This exploratory study intends to examine what works and what does not among South Asian (Pakistani and Bangladeshi heritage) females and black male adult learners in FE. A mixed-method study was carried out using questionnaires and focus groups with 68 ethnic minority students in three further education colleges in England. The combination of the results showed that being a member of a minority culture and/or religion may increase feelings of isolation in academic settings; teaching staff who are knowledgeable about the student’s culture increase feelings of inclusion; and role models are crucially important. Results are discussed in light of British data of school experiences of ethnic minority learners

'You were quiet - I did all the marching': Research processes involved in hearing the voices of South Asian girls

This article is available open access through the publisher’s website at the link below. Copyright @ 2011 A B Academic Publishers.This article provides insights into the outcomes of reflection following two interview approaches used to explore narratives of the lived, individual experiences of South-Asian girls living in West London. In attempting to illuminate and re-present the cultural experiences as told by these girls, the choice of interview approach became critical in allowing the voices to be effectively heard (Rogers, 2005). This article therefore considers how a semi-structured interview approach offered valuable insights into the girls' experiences but became constraining for both researcher and participant in unveiling the complexity and depth of their lives. These constraints emerged through reflection by both participants and researcher. As a result of reflexivity during the research process, the researcher moved towards the use of research conversations during the second phase of the study. Ultimately the study revealed how the girls felt empowered by the opportunity to narrate their individual experiences and tell of their lives. In narrating their reflections on being part of the research, there was a clear recognition that the process facilitated the articulation of new voices and ‘multi-voicedness’ (Moen, 2006