A habitable fluvio-lacustrine environment at Yellowknife Bay, Gale crater, Mars.

The Curiosity rover discovered fine-grained sedimentary rocks, which are inferred to represent an ancient lake and preserve evidence of an environment that would have been suited to support a martian biosphere founded on chemolithoautotrophy. This aqueous environment was characterized by neutral pH, low salinity, and variable redox states of both iron and sulfur species. Carbon, hydrogen, oxygen, sulfur, nitrogen, and phosphorus were measured directly as key biogenic elements; by inference, phosphorus is assumed to have been available. The environment probably had a minimum duration of hundreds to tens of thousands of years. These results highlight the biological viability of fluvial-lacustrine environments in the post-Noachian history of Mars.

The role of microbes in accretion, lamination and early lithification of modern marine stromatolites.

For three billion years, before the Cambrian diversification of life, laminated carbonate build-ups called stromatolites were widespread in shallow marine seas. These ancient structures are generally thought to be microbial in origin and potentially preserve evidence of the Earth's earliest biosphere. Despite their evolutionary significance, little is known about stromatolite formation, especially the relative roles of microbial and environmental factors in stromatolite accretion. Here we show that growth of modern marine stromatolites represents a dynamic balance between sedimentation and intermittent lithification of cyanobacterial mats. Periods of rapid sediment accretion, during which stromatolite surfaces are dominated by pioneer communities of gliding filamentous cyanobacteria, alternate with hiatal intervals. These discontinuities in sedimentation are characterized by development of surface films of exopolymer and subsequent heterotrophic bacterial decomposition, forming thin crusts of microcrystalline carbonate. During prolonged hiatal periods, climax communities develop, which include endolithic coccoid cyanobacteria. These coccoids modify the sediment, forming thicker lithified laminae. Preservation of lithified layers at depth creates millimetre-scale lamination. This simple model of modern marine stromatolite growth may be applicable to ancient stromatolites.

Development of a highly polymorphic STR marker for identity testing purposes at the human androgen receptor gene (HUMARA).

We developed a non-isotopic method which improves the technical quality of the X-linked HUMARA locus typing process. The use of formamide and a low concentration of acrylamide increased resolution and sharpness of HUMARA alleles in silver-stained polyacrylamide gels. In addition, the construction of an allelic ladder containing amplified sequence of 9 alleles (even-numbered alleles) of the HUMARA locus, allows confident, rapid and precise assignment of discretely defined alleles. Allele and genotype frequencies for the HUMARA locus were determined in a French Canadian population sample. Observed genotype frequencies in females conformed to Hardy-Weinberg expectations. Furthermore, the HUMARA locus is highly polymorphic with 18 observed alleles and an heterozygosity value of 89.3%. Also, this locus has average powers of discrimination of 97.8% and 88.7% for testing samples of female and male origin, respectively. In the French Canadian population, the average probability of excluding a random man as the father in paternity analysis when both mother and daughter are tested for this locus is 88.0%. Together, the results indicate that the HUMARA locus provides a highly discriminatory system that is appropriate for the purposes of forensic identification and paternity testing involving a female child.

Analysis of allele distribution for six short tandem repeat loci in the French Canadian population of Québec.

Short tandem repeat (STR) loci represent a rich source of highly polymorphic markers in the human genome which are useful for the purposes of forensic identification and determination of biological relatedness of individuals. Here, as a part of an ongoing extensive study, we report the analysis of a multilocus genotype survey of 642 to 870 chromosomes in the French Canadian Caucasian population of Québec at six STR loci. The loci HUMCSF1PO, HUMTPOX, HUMTH01, HUMF13A01, HUMFESFPS, and HUMvWA were typed using two multiplex polymerase chain reactions (PCR). Amplified DNA samples were subsequently analyzed by polyacrylamide gel electrophoresis followed by silver staining. The heterozygote frequencies of the loci range from 0.614 to 0.820 (0.661 to 0.818 expected) and the number of alleles from 7 to 12 per locus. Although statistically significant deviation from Hardy-Weinberg expectations of genotype frequencies was noted at some loci by one or more tests, in general, the genotype frequencies are well estimated from the product of allele frequencies at all loci. The most frequent six-locus genotype is expected to occur in the French Canadian population with a frequency of 3.50 by 10(-5) and together, these six loci have an average probability of discrimination of 0.9999985. The study presented here indicates that these six STR loci are informative genetic markers for identity testing purposes in the French Canadian Caucasian population of Québec.

2-Sulfotrehalose, a novel osmolyte in haloalkaliphilic archaea.

A novel 1-->1 alpha-linked glucose disaccharide with sulfate at C-2 of one of the glucose moieties, 1-(2-O-sulfo-alpha-D-glucopyranosyl)-alpha-D-glycopyranose, was found to be the major organic solute accumulated by a Natronococcus sp. and several Natronobacterium species. The concentration of this novel disaccharide, termed sulfotrehalose, increased with increasing concentrations of external NaCl, behavior consistent with its identity as an osmolyte. A variety of noncharged disaccharides (trehalose, sucrose, cellobiose, and maltose) were added to the growth medium to see if they could suppress synthesis and accumulation of sulfotrehalose. Sucrose was the most effective in suppressing biosynthesis and accumulation of sulfotrehalose, with levels as low as 0.1 mM being able to significantly replace the novel charged osmolyte. Other common osmolytes (glycine betaine, glutamate, and proline) were not accumulated or used for osmotic balance in place of the sulfotrehalose by the halophilic archaeons.

The TATA motif is a target for efficient transcriptional activation and nerve growth factor induction of the peripherin gene.

Three proximal elements, PER1, PER2, and PER3, have been implicated in the regulation of peripherin gene expression. PER1 contains the TATA motif and was identified as the principal mediator of neuronal specificity. Here, we demonstrate by transfection of constructs mutated in PER1 that the in vitro protein binding activity of PER1 is irrelevant to its function. However, mutations or substitutions in the TATA box decreased promoter activity by up to 80%. We have investigated this unusual preference for a particular TATA sequence in PC12 cells. In these cells, nerve growth factor induces neuronal differentiation, increasing peripherin gene expression 3-4-fold, while dexamethasone elicits chromaffin differentiation and a 3-fold decrease in peripherin mRNA. Experiments with stably transfected PC12 cells revealed that the specific TATA box of the peripherin gene was crucial for nerve growth factor response. However, it did not affect dexamethasone down-regulation. Therefore, nerve growth factor acts through an element essential for neuronal peripherin gene expression. The results predict that proteins interacting in the vicinity of the TATA box, by inference factors associated with the preinitiation complex, are important for peripherin gene regulation and provide new insights into the mechanisms underlying neuronal differentiation.

Lithofacies and biofacies of mid-Paleozoic thermal spring deposits in the Drummond Basin, Queensland, Australia.

The Devonian to Carboniferous sinters of the Drummond Basin, Australia, are among the oldest well established examples of fossil subaerial hot springs. Numerous subaerial and subaqueous spring deposits are known from the geological record as a result of the occurrence of economic mineral deposits in many of them. Some are reported to contain fossils, but very few have been studied by paleobiologists; they represent an untapped source of paleobiological information on the history of hydrothermal ecosystems. Such systems are of special interest, given the molecular biological evidence that thermophilic bacteria lie near the root of the tree of extant life. The Drummond Basin sinters are very closely comparable with modern examples in Yellowstone National Park and elsewhere. Thirteen microfacies are recognisable in the field, ranging from high temperature apparently abiotic geyserite through various forms of stromatolitic sinter probably of cyanobacterial origin to ambient temperature marsh deposits. Microfossils in the stromatolites are interpreted as cyanobacterial sheaths. Herbaceous lycopsids occur in the lower temperature deposits.

Transcriptional activation of the neuronal peripherin-encoding gene depends on a G + C-rich element that binds Sp1 in vitro and in vivo.

Peripherin (Prph) is a type-III intermediate filament (IF) protein principally synthesized in peripheral nervous system neurons. We have previously shown that three regulatory elements, PER1, PER2 and PER3, in the first 98 bp of the Prph gene promoter, were sufficient to direct cell-type specific expression of a reporter gene [Desmarais et al., EMBO J. 11 (1992) 2971-2980]. Of these elements, PER1 was found to be important for cell-type specificity, but required the presence of other elements for transcriptional activity. Here, we show that PER3 is a stronger activator than PER2 and that it can stimulate cell-type-specific transcription when combined with PER1. We have characterized the G + C-rich PER3 element for its ability to bind trans-acting factors. Gel retardation and methylation interference (MI) assays show that PER3 binds transcription factor Sp1. In addition, an anti-Sp1 antibody recognizes the PER3 DNA-binding protein. A 3-bp mutation abrogating the capacity of PER3 to bind Sp1 in vitro completely abolished expression of the reporter gene construct containing only PER3 and PER1, while in a construct containing the first 256 bp of the Prph promoter, it led to an 80% decrease with respect to the control wild-type construct. Finally, by co-transfection of a Sp1-expressing plasmid, we show that Sp1 can stimulate transcription from a reporter gene containing the PER3 sequence. Together, these results indicate that interactions between Sp1 and the proteins binding PER1 are involved in the control of the Prph gene.

Saccharopolyspora hirsuta 367 encodes clustered genes similar to ketoacyl synthase, ketoacyl reductase, acyl carrier protein, and biotin carboxyl carrier protein.

The actI gene, encoding a component of the actinorhodin polyketide synthase of Streptomyces coelicolor, was used to identify and clone a homologous 11.7 kb BamHI DNA fragment from Saccharopolyspora hirsuta 367. The cloned fragment complemented actinorhodin production in a strain of Streptomyces coelicolor bearing a mutant actI gene. The DNA sequence of a 5.1 kb fragment revealed 6 open reading frames (ORF). ORF1 does not resemble any known DNA or deduced protein sequence, while the deduced protein sequence of ORF2 resembles that of biotin carboxyl carrier proteins. Based on the similarity to deduced protein sequences from cloned genes of polyketide producers, ORF3 would code for a ketoreductase, ORF4 and ORF5 for the putative heterodimeric beta-ketoacyl synthase, and ORF6 for an acyl carrier protein.

Cell-specific transcription of the peripherin gene in neuronal cell lines involves a cis-acting element surrounding the TATA box.

Peripherin is a neurone-specific intermediate filament protein expressed mostly in the peripheral nervous system. To localize sequences that are important for the regulation of peripherin gene transcription, we have functionally dissected its promoter. Transfection into different cell lines and deletion mapping of peripherin-lacZ hybrid constructs indicated that the first 98 bp preceding the transcription start site of the gene were sufficient to confer cell-type specific expression. DNase I footprinting experiments revealed three protected sequences in this region, that were named PER1, PER2 and PER3. The PER2 and PER3 elements, localized between -98 to -46, interact with proteins that seem widely distributed. Deletion of these elements severely decreased the level of reporter gene activity. The PER1 element, which overlaps the TATA box, interacts with a DNA-binding protein prevailing in peripherin expressing cell lines. However, the core promoter, which contains the PER1 element, was inefficient in driving gene expression. Experiments designed to test the contribution of each element showed that PER2 and PER3 were important in determining the level of expression, while PER1 was important for cell-type specificity. In fact the polyoma virus enhancer linked to the peripherin gene core promoter was found to limit reporter gene activity to peripherin expressing cell lines. Together, these experiments indicate that co-operative interactions between different regions of the promoter are necessary for efficient and cell-type specific transcription of the peripherin gene in a subset of neuronal cells.

Saccharopolyspora hirsuta strain 367 releases JHJ-1, a bacteriophage capable of propagation on old mycelium.

Bacteriophage JHJ-1 was isolated from Saccharopolyspora hirsuta strain 367 NRRL 12045 as an endogenous but virulent phage. The plaque size was not self-limiting, since a few p.f.u. could completely lyse a lawn. Electron microscopy showed that this phage belonged to group B of Bradley's morphological classification. The JHJ-1 genome is a linear DNA molecule of 41.1 kbp with cohesive ends and a G + C content of 68.8-70.0 mol%. The DNA cleavage map was established for 12 restriction endonucleases. The host range is apparently very narrow, being limited to two strains of S. hirsuta (NRRL 12045 and NRRL B-5792). However, JHJ-1 did not lytically infect S. hirsuta strain 367 UC 8106. Phage JHJ-1 was shown, by Southern blot analysis, to lysogenize both S. hirsuta NRRL 12045 and UC 8106. It thus appears to behave as a virulent mutant of a temperate phage on one, but not on the other, JHJ-1 lysogen.

Stable carbon isotope fractionation in the search for life on early Mars.

Isotopic measurements and, more specifically, ratios of 13C to 12C in organic relative to inorganic deposits, are useful in reconstructing past biological activity on Earth. Organic matter has a lower ratio of 13C to 12C due largely to the preferential fixation of 12C over the heavier isotope by the major carbon-fixation enzyme, ribulose-1,5-bisphosphate carboxylase/oxygenase, although other factors (e.g., availability of source carbon, fixation by other carboxylating enzymes and diagenesis of organic material) also contribute to fractionation. Would carbon isotope discrepancies between inorganic and organic carbon indicate past biological activity on Mars? In order to answer this question, we analyse what is known about terrestrial biologic and abiologic carbon fixation and its preservation in the fossil record, and suggest what the isotope discrimination during possible biologic and abiologic carbon fixation on Mars might have been like. Primarily because isotopic signatures of abiotically fixed carbon overlap with those of biotic fixation, but also because heterotrophy does not significantly alter the isotopic signature of ingested carbon, fractionation alone would not be definitive evidence for life. However, a narrow range of fractionation, including no fractionation, would suggest biotic processes. Never-the-less, isotopic ratios in organic deposits on Mars would be extremely useful in analysing prebiotic, if not biotic, carbon transformations on Mars.

[Exploratory analysis of mental health in an unemployment situation : the case of workers in the manufacturing sector of eastern Montréal (Part 1).]. / Analyse exploratoire de pratiques de santé mentale en situation de chômage : le cas d'ouvriers et d'ouvrières du secteur manufacturier de l'Est de Montréal (première partie).

The objectives of this research are to take the inventory of the psychosocial mechanisms that promote the unemployed individual's equilibrium, and to draw the profile of mental health practices existing in a homogenous group of unemployed persons in the manufacturing sector. In the first part, the authors review the methodology used in the course of their study and present a global analysis of the daily experiences of unemployed individuals, by showing the means they have put into effect to ensure their subsistance and that of their family. The second part seeks to provide an original viewpoint to the issue of mental health. The analysis includes an inventory of mental health practices followed by a brief description of techniques used to establish mutual aid networks.

[Exploratory analysis of practices in mental health in an unemployment situation : the case of workers in the manufacturing sector of Eastern Montréal (Part 2).]. / Analyse exploratoire de pratiques de santé mentale en situation de chômage : le cas d'ouvriers et d'ouvrières du secteur manufacturier de l'Est de Montréal (deuxième partie).

In this article, the authors present results stemming from the exploratory analysis of mental health practices that are used by a group of unemployed workers. The study presents five types of practices: the enhancement of the unemployed individual's experience, institutional consultation within the health care system, anticipation, self-actualization and changes to the unemployment situation. These various mental health practices, demonstrated among a homogenous group of unemployed individuals in the manufacturing sector, promote a wider reflexion of intervention methods.

Methanogenesis in big soda lake, nevada: an alkaline, moderately hypersaline desert lake.

Incubated sediment slurries from Big Soda Lake, Nevada, produced significant levels of CH(4), and production was inhibited by 2-bromoethanesulfonic acid and by autoclaving. Methane production was stimulated by methanol, trimethylamine, and, to a lesser extent, methionine. Surprisingly, hydrogen, acetate, and formate amendments provided only slight or no stimulation of methanogenesis. Methane production by sediment slurries had a pH optimum of 9.7. A methanol-grown enrichment culture containing a small, epifluorescent coccus as the predominant organism was recovered from sediments. The enrichment grew best when FeS or autoclaved sediment particles were included in the media, had a pH optimum of 9.7, and produced CH(4) from CH(3)OH. The methane formed by methanolgrown enrichment cultures was depleted in C by 72 to 77 per thousand relative to the methanol.

[The networking model (example and commentary).]. / Le modèle d'intervention auprès du réseau (illustration et commentaire).

The article presents a new short team made of intervention in a situation crisis in psychiatry. This new approach developed by Ross V. Speck and his collaborators aims at involving the relatives and friends of the family in crisis in order to help the seeing through of a dead-end situation. The authors, after describing the main intervention criteria as well as the process and role of the mediators, analyse some of the parameters differentiating this model from the traditional approaches. In their commentary they use a bio-psychosocial approach to mental illness.