Modulation of the transferrin receptor during DMSO-induced differentiation in HL-60 cells

When HL-60 cells are induced to differentiate by dimethyl sulfoxide along a granulocytic pathway there is a fivefold decrease in the total number of transferrin receptors within 3 days, as compared to untreated cells. This decrease is due primarily to a rapid decline in the synthesis of the receptor rather than an increase in the degradation of the receptor. The decrease in transferrin receptor synthesis is a specific and early event that precedes the cessation of cell proliferation, differentiation, and the decrease in total protein synthesis.     

Ecological implications of climate change will include surprises

In addition to assessing the impacts of CO₂ doubling on environment and society, more consideration is needed to estimate extreme events or surprises. This is particularly important at the intersection of disciplines like climate and ecology because the potential for large discontinuities is high given all the possible climate/biota interactions. The vast disparities in scales encountered by those working in traditional ecology (typically 20 m) and climatology (typically 200 km) make diagnoses of such interactions difficult, but these can be addressed by an emerging research paradigm we call strategic cyclical scaling (SCS). The need to anticipate outlier events and assign them subjective probabilities suggests emphasis on interdisciplinary research associations. The desire to reduce societal vulnerability to such events suggests the need to build adaptive management and diverse economic activities into social organizations. The effectiveness of adaptation responses to anticipated climatic changes is complicated when consideration of transient changes, regional disturbances, large unforseeable natural fluctuations and surprises are considered. Slowing down the rate of disturbances and decreasing vulnerability are advocated as the most prudent responses to the prospect of human-induced climatic changes.     

Glucose-6-phosphate dehydrogenase deficiency and infection: a study of hospitalized patients in Iran.

The Mediterranean variant of glucose-6-phosphate dehydrogenase (G6PD) is functionally deficient and found in a variety of cell types of affected individuals, including both erythocytes and neutrophils. To determine if the presence of this sex-linked gene is associated to any degree with the occurrence of severe bacterial infection, a study of hospitalized male patients in Iran was undertaken. As determined by erythrocyte assay, allele prevalence in male patients with infection was 22% vs. 12% in a patient group matched for the absence of other risk factors for infection and 6% in a second group who had additional risk factors for infection. When the control and patient groups were considered together the difference between the frequency of G6PD deficiency (10.2%) was significantly different from that found in the infected patients (p less than .05). Furthermore, the mean age of infected patients with G6PD deficiency was significantly less than that of infected patients without G6PD deficiency or non-infected control groups. These data suggest that host defenses may be altered in G6PD deficiency so that bacterial infections are more severe. Alternatively, G6PD deficiency and infection might represent concomittant risk factors which lead to hospitalization during bacterial infection. Potential mechanisms by which host defenses might be altered in G6PD deficiency are discussed.     

The architecture and contraction time of intrinsic foot muscles

Although critical for effective human locomotion and posture, little data exists regarding the segmentation, architecture and contraction time of the human intrinsic foot muscles. To address this issue, the Abductor Hallucis (AH), Abductor Digiti Minimi (ADM), Flexor Digitorum Brevis (FDB) and Extensor Digitorum Brevis (EDB) were investigated utilizing a cadaveric dissection and a non-invasive whole muscle mechanomyographic (wMMG) technique. The segmental structure and architecture of formaldehyde-fixed foot specimens were determined in nine cadavers aged 60–80 years. The wMMG technique was used to determine the contraction time (Tc) of individual muscle segments, within each intrinsic foot muscle, in 12 volunteers of both genders aged between 19 and 24 years.While the pattern of segmentation and segmental –architecture (e.g. fibre length) and –Tc of individual muscle segments within the same muscle were similar, they varied between muscles. Also, the average whole muscle Tc of FDB was significantly (p < 0.05) shorter (faster) (Tc = 58 ms) than in all other foot muscles investigated (ADM Tc = 72 ms, EDB Tc = 72 ms and ABH Tc = 69 ms). The results suggest that the architecture and contraction time of the FDB reflect its unique direct contribution, through toe flexion, to postural stability and the rapid development of ground reaction forces during forceful activities such as running and jumping.     

In vivo transgenic mutation assays

Transgenic rodent gene-mutation models provide relatively quick and statistically reliable assays for gene mutations in the DNA from any tissue. This report summarizes those issues that have been agreed upon at a previous IWGT meeting [Environ. Mol. Mutagen. 35 (2000) 253], and discusses in depth those issues for which no consensus was reached before. It was previously agreed that for regulatory applications, assays should be based upon neutral genes, be generally available in several laboratories, and be readily transferable. For phage-based assays, five to ten animals per group should be analyzed, assuming a spontaneous mutant frequency (MF) of approximately 3x10(-5) mutants/locus and 125,000-300,000 plaque or colony forming units (pfu or cfu) per tissue per animal. A full set of data should be generated for a vehicle control and two dose groups. Concurrent positive control animals are only necessary during validation, but positive control DNA must be included in each plating. Tissues should be processed and analyzed in a blocked design, where samples from negative control, positive control and each treatment group are processed together. The total number of pfus or cfus and the MF for each tissue and animal are reported. Statistical tests should consider the animal as the experimental unit. Nonparametric statistical tests are recommended. A positive result is a statistically significant dose-response and/or statistically significant increase in any dose group compared to concurrent negative controls using an appropriate statistical model. A negative result is a statistically non-significant change, with all mean MFs within two standard deviations of the control. During the current workshop, a general protocol was agreed in which animals are treated daily for 28 consecutive days and tissues sampled 3 days after the final treatment. This recommendation could be modified by reducing or increasing the number of treatments or the length of the treatment period, when scientifically justified. Normally male animals alone are sufficient and normally at least one rapidly proliferating and one slowly proliferating tissue should be sampled. Although, as agreed previously, sequencing data are not normally required, they might provide useful additional information in specific circumstances, mainly to identify and correct for clonal expansion and in some cases to determine a mechanism associated with a positive response.     

Quantifying division of labor: borrowing tools from sociology,sociobiology, information theory,landscape ecology,and biogeography

How do we quantify division of labor? We review several fields (sociology, landscape ecology, statistics, information theory, and biogeography) that have been cognizant of these questions and been somewhat successful at answering them. We review fourteen indices for quantifying division of labor, sensu lato, which can be categorized into four families: Shannon’s index/entropy, Simpson’s index, geometric mean, and standard/absolute deviation (including coefficients of variation). We argue that those indices using matrix inputs will simultaneously quantify the interplay between all individuals and all tasks and will thus best capture the essence of division of labor. Received 29 March 2006; revised 16 November 2006; accepted 12 February 2007.     

Semi-automated Imaging of Tissue-specific Fluorescence in Zebrafish Embryos

Zebrafish embryos are a powerful tool for large-scale screening of small molecules. Transgenic zebrafish that express fluorescent reporter proteins are frequently used to identify chemicals that modulate gene expression. Chemical screens that assay fluorescence in live zebrafish often rely on expensive, specialized equipment for high content screening. We describe a procedure using a standard epifluorescence microscope with a motorized stage to automatically image zebrafish embryos and detect tissue-specific fluorescence. Using transgenic zebrafish that report estrogen receptor activity via expression of GFP, we developed a semi-automated procedure to screen for estrogen receptor ligands that activate the reporter in a tissue-specific manner. In this video we describe procedures for arraying zebrafish embryos at 24-48 hours post fertilization (hpf) in a 96-well plate and adding small molecules that bind estrogen receptors. At 72-96 hpf, images of each well from the entire plate are automatically collected and manually inspected for tissue-specific fluorescence. This protocol demonstrates the ability to detect estrogens that activate receptors in heart valves but not in liver.     

A leucine triplet repeat sequence (LXX)4 in p6gag is important for Vpr incorporation into human immunodeficiency virus type 1 particles.

Incorporation of Vpr into human immunodeficiency virus type 1 (HIV-1) virions is mediated by the Gag protein, independently of other viral components. We have coexpressed Vpr and Gag constructs in a vaccinia virus expression system in order to map the region of Gag involved in Vpr packaging. Deletion of the carboxyl-terminal p6 region of Gag impaired the ability of Gag to package Vpr. To confirm the role of p6 in Vpr packaging, Rous sarcoma virus (RSV)-HIV chimeras containing HIV-1 p6 were constructed. Although RSV Gag does not package Vpr into virus particles, a chimera containing HIV-1 p6 is sufficient for Vpr incorporation. To map the region of p6 involved in Vpr packaging, a series of p6 point mutations and deletion mutations was analyzed. Mutations in the N-terminal p6 proline-rich domain, for which preliminary evidence shows a marked decrease in virion incorporated RNA, did not affect Vpr incorporation. Deletion of residues 1 to 31 of HIV-1 p6 did not affect Vpr packaging, but residues 35 to 47, including an (LXX)4 domain, were required for Vpr incorporation into virus particles.