The Discoidin I Gene Family of Dictyostelium Discoideum Is Linked to Genes Regulating Its Expression

The discoidin I protein has been studied extensively as a marker of early development in the cellular slime mold Dictyostelium discoideum. However, like most other developmentally regulated proteins in this system, no reliable information was available on the linkage of the discoidin genes to other known genes. Analysis of the linkage of the discoidin I genes by use of restriction fragment length polymorphisms revealed that all three discoidin I genes as well as a pseudogene are located on linkage group II. This evidence is consistent with the discoidin I genes forming a gene cluster that may be under the control of a single regulatory element. The discoidin I genes are linked to three genetic loci (disA, motA, daxA) that affect the expression of the discoidin I protein. Linkage of the gene family members to regulatory loci may be important in the coordinate maintenance of the gene family and regulatory loci. A duplication affecting the entire discoidin gene family is also linked to group II; this appears to be a small tandem duplication. This duplication was mapped using a DNA polymorphism generated by insertion of the Tdd-3 mobile genetic element into a Tdd-2 element flanking the gamma gene. A probe for Tdd-2 identified a restriction fragment length polymorphism in strain AX3K that was consistent with generation by a previously proposed Tdd-3 insertion event. A putative duplication or rearrangement of a second Tdd-2 element on linkage group IV of strain AX3K was also identified. This is the first linkage information available for mobile genetic elements in D. discoideum.     

Conflict and reconciliation in two groups of crab-eating monkeys differing in social status by birth

Two groups of captive macaques (M. fascicularis) were studied at Kassel University, Germany. One included animals whose mothers were high-ranking, another, those whose mothers were low-ranking. The first group was a despotic community in which conflicts were severe and occurred mainly between single individuals; the reconciliation tendency was weak, the male leader was the controlling animal, and the affiliative preferences were marked. The second group was an egalitarian community split into two mutually hostile conalitions; the conflicts were less severe, the tendency for reconciliation was strong, the male leader could control only his own bloc and had no strong affiliative ties with other group members.     

Isolation and Ex Vivo Culture of Vδ1+CD4+γδ T Cells,an Extrathymic αβT-cell Progenitor

The thymus, the primary organ for the generation of αβ T cells and backbone of the adaptive immune system in vertebrates, has long been considered as the only source of αβT cells. Yet, thymic involution begins early in life leading to a drastically reduced output of naïve αβT cells into the periphery. Nevertheless, even centenarians can build immunity against newly acquired pathogens. Recent research suggests extrathymic αβT cell development, however our understanding of pathways that may compensate for thymic loss of function are still rudimental. γδ T cells are innate lymphocytes that constitute the main T-cell subset in the tissues. We recently ascribed a so far unappreciated outstanding function to a γδ T cell subset by showing that the scarce entity of CD4⁺ Vδ1⁺γδ T cells can transdifferentiate into αβT cells in inflammatory conditions. Here, we provide the protocol for the isolation of this progenitor from peripheral blood and its subsequent cultivation. Vδ1 cells are positively enriched from PBMCs of healthy human donors using magnetic beads, followed by a second step wherein we target the scarce fraction of CD4⁺ cells with a further magnetic labeling technique. The magnetic force of the second labeling exceeds the one of the first magnetic label, and thus allows the efficient, quantitative and specific positive isolation of the population of interest. We then introduce the technique and culture condition required for cloning and efficiently expanding the cells and for identification of the generated clones by FACS analysis. Thus, we provide a detailed protocol for the purification, culture and ex vivo expansion of CD4⁺ Vδ1⁺γδ T cells. This knowledge is prerequisite for studies that relate to this αβT cell progenitor`s biology and for those who aim to identify the molecular triggers that are involved in its transdifferentiation.     

Fishers' knowledge and seahorse conservation in Brazil

From a conservationist perspective, seahorses are threatened fishes. Concomitantly, from a socioeconomic perspective, they represent a source of income to many fishing communities in developing countries. An integration between these two views requires, among other things, the recognition that seahorse fishers have knowledge and abilities that can assist the implementation of conservation strategies and of management plans for seahorses and their habitats. This paper documents the knowledge held by Brazilian fishers on the biology and ecology of the longsnout seahorse Hippocampus reidi. Its aims were to explore collaborative approaches to seahorse conservation and management in Brazil; to assess fishers' perception of seahorse biology and ecology, in the context evaluating potential management options; to increase fishers' involvement with seahorse conservation in Brazil. Data were obtained through questionnaires and interviews made during field surveys conducted in fishing villages located in the States of Piauí, Ceará, Paraíba, Maranhão, Pernambuco and Pará. We consider the following aspects as positive for the conservation of seahorses and their habitats in Brazil: fishers were willing to dialogue with researchers; although captures and/or trade of brooding seahorses occurred, most interviewees recognized the importance of reproduction to the maintenance of seahorses in the wild (and therefore of their source of income), and expressed concern over population declines; fishers associated the presence of a ventral pouch with reproduction in seahorses (regardless of them knowing which sex bears the pouch), and this may facilitate the construction of collaborative management options designed to eliminate captures of brooding specimens; fishers recognized microhabitats of importance to the maintenance of seahorse wild populations; fishers who kept seahorses in captivity tended to recognize the condtions as poor, and as being a cause of seahorse mortality.     

A new genus of water mites (Acari,Hydrachnidia, Wettinidae) from bromeliad phytotelmata in the Brazilian Atlantic rainforest

Adults of Bromeliacarus cardoso gen. n., sp. n. are described from phytotelmata of Quesnelia arvensis (Vellozo) Mez. (Bromeliaceae) in the subtropical area of the Atlantic rainforest, São Paulo State, Brazil. The new genus Bromeliacarus is proposed and diagnosed, based primarily on the autapomorphic presence of 7–9 pairs of acetabula flanking the gonopore. A possible relationship between Bromeliacarus and other Wettinidae are discussed.     

The Use of DNA Probes for Taxonomic Study of Dictyostelium Wild Isolates

The classification of 27 wild isolates assigned to Dictyostelium discoideum on the basis of morphological criteria was reexamined using probes specific for DNA sequences cloned from the type strain NC4. These probes included ones specific for ribosomal spacer DNA regions and for a ribosomal RNA coding sequence, as well as probes for two chromosomal gene families (actin and discoidin) and for the DIRS-1 transposable element. Four isolates (AC4, WS526, WS584 and ZA3A) which had previously been shown to have unusual mating characteristics were distinctly different from other isolates. We interpret these differences as indicating that the four atypical isolates represent species other than D. discoideum. Probes for the ribosomal spacer DNA either did not hybridize to the DNA of these four isolates or had decreased levels of hybridization to EcoRI restriction fragments of different lengths to that observed with the type strain. With the discoidin probe, all isolates had DNA fragments that hybridized but AC4, WS526, WS584 and ZA3A lacked a pair of fragments that were conserved in NC4 and other isolates. With the actin probe, AC4, WS526, WS584 and ZA3A lacked numerous fragments that the other isolates shared with NC4. The DIRS-1 probes showed strong hybridization with ZA3A and weak hybridization to the other three isolates; however, the major EcoRI fragment in WS526 and WS584 was smaller than that in NC4 while ZA3A and AC4 had fragments of similar size to that in NC4.(ABSTRACT TRUNCATED AT 250 WORDS)     

Measuring the structural impact of mutations on cytochrome P450 21A2, the major steroid 21-hydroxylase related to congenital adrenal hyperplasia

Abstract

Congenital adrenal hyperplasia is an inherited autosomal recessive disorder related to deficient cortisol synthesis. The deficiency of steroid 21-hydroxylase (cytochrome P450 21A2), an enzyme involved in cortisol synthesis, is responsible for ～95% of cases of congenital adrenal hyperplasia. This metabolic disease exhibits three clinical forms: salt-wasting, simple virilizing, and non-classical form, which are divided according to the degree of severity. In the present study, structural and mutational analyses were performed in order to identify the structural impact of mutations on cytochrome P450 21A2 and correlate them with patient clinical severity. The following mutations were selected: arginine-356 to tryptophan (R356W), proline-30 to leucine (P30L), isoleucine-172 to asparagine (I172N), valine-281 to leucine (V281L), and the null mutation glutamine-318 (Q318X). Our computational approach mapped the location of residues on P450 and identified their implications on enzyme electrostatic potential mapping to progesterone and heme binding pockets. Using molecular dynamics simulations, we analyzed the structural stability of ligand binding and protein structure, as well as possible conformational changes at the catalytic pocket that leads to impairment of enzymatic activity. Our study sheds light on the impact structural mutations have over steroid 21-hydroxylase structure-function in the cell.

Communicated by Ramaswamy H. Sarma