A recombination outside the BB deletion refines the location of the X linked retinitis pigmentosa locus RP3.

Genetic loci for X-linked retinitis pigmentosa (XLRP) have been mapped between Xp11.22 and Xp22.13 (RP2, RP3, RP6, and RP15). The RP3 gene, which is responsible for the predominant form of XLRP in most Caucasian populations, has been localized to Xp21.1 by linkage analysis and the map positions of chromosomal deletions associated with the disease. Previous linkage studies have suggested that RP3 is flanked by the markers DXS1110 (distal) and OTC (proximal). Patient BB was thought to have RP because of a lesion at the RP3 locus, in addition to chronic granulomatous disease, Duchenne muscular dystrophy (DMD), mild mental retardation, and the McLeod phenotype. This patient carried a deletion extending approximately 3 Mb from DMD in Xp21.3 to Xp21.1, with the proximal breakpoint located approximately 40 kb centromeric to DXS1110. The RP3 gene, therefore, is believed to reside between DXS1110 and the proximal breakpoint of the BB deletion. In order to refine the location of RP3 and to ascertain patients with RP3, we have been analyzing several XLRP families for linkage to Xp markers. Linkage analysis in an American family of 27 individuals demonstrates segregation of XLRP with markers in Xp21.1, consistent with the RP3 subtype. One affected mate shows a recombination event proximal to DXS1110. Additional markers within the DXS1110-OTC interval show that the crossover is between two novel polymorphic markers, DXS8349 and M6, both of which are present in BB DNA and lie centromeric to the proximal breakpoint. This recombination places the XLRP mutation in this family outside the BB deletion and redefines the location of RP3.     

Past vegetation changes in the Brazilian Pantanal arboreal–grassy savanna ecotone by using carbon isotopes in the soil organic matter

Measurements of the organic carbon inventory, its stable isotopic composition and radiocarbon content were used to deduce vegetation history from two soil profiles in arboreal and grassy savanna ecotones in the Brazilian Pantanal. The Pantanal is a large floodplain area with grass-dominated lowlands subject to seasonal flooding, and arboreal savanna uplands which are only rarely flooded. Organic carbon inventories were lower in the grassy savanna site than in the upland arboreal savanna site, with carbon decreasing exponentially with depth from the surface in both profiles. Changes in ¹³C of soil organic matter (SOM) with depth differed markedly between the two sites. Differences in surface SOM ¹³C values reflect the change from C₃ to C₄ plants between the sites, as confirmed by measurements of ¹³C of vegetation and the soil surface along a transect between the upland closed-canopy forest and lowland grassy savanna. Changes of ¹³C in SOM with depth at both sites are larger than the 3–4 per mil increases expected from fractionation associated with organic matter decomposition. We interpret these as recording past changes in the relative abundance of C₃ and C₄ plants at these sites. Mass balances with ¹⁴C and ¹³C suggest that past vegetational changes from C₃ to C₄ plants in the grassy savanna, and in the deeper part of the arboreal savanna, occurred between 4600 and 11 400 BP, when major climatic changes were also observed in several places of the South American Continent. The change from C₄ to C₃, observed only in the upper part of the arboreal savanna, was much more recent (1400 BP), and was probably caused by a local change in the flooding regime.     

Studies on the uptake and intracellular replication of Legionella pneumophila in protozoa and in macrophage-like cells

Abstract Legionella pneumophila strains isolated from different sources were tested for their host range in the protists Acanthamoeba castellanii, Hartmannella vermiformis and Entamoeba histolytica . It has been shown that A. castellanii and H. vermiformis but not E. histolytica support the intracellular replication of L. pneumophila . Furthermore it could be demonstrated that in vivo virulence in the guinea pig and the intracellular growth in U937 cells coincides with the capability to replicate intracellularly in A. castellanii at 37°C. The infectivity of L. pneumophila that had sustained a 48 hours nutrient deprivation was not significantly different from that of legionellae grown to log-phase on BCYE plates. In contrast the nutrient limitation on A. castellanii increased the amount of intracellular legionellae at the beginning of infection. An initial opsonin independent attachement stage of legionellae to U937 cells was demonstrated by scanning electron microscopy. In contrast, L. pneumophila's capability of stable or long term attachmennt to A. castellanii was shown to be inefficient.     

HYDROBIIDAE (GASTROPODA: HYDROBIOIDEA) FROM THE RIBEIRA VALLEY, S.E. BRAZIL, WITH DESCRIPTIONS OF TWO NEW CAVERNICOLOUS SPECIES

Potamolithus karsticus n. sp. and Potamolithus troglo-bius n.sp., two Brazilian aquatic cavesnails (Gastropoda: Hydrobiidae),are described. P. troglobius is blind and depigmented, and isthe first stygobiontic snail to be described from Brazil Additionally, specimens of Potamolithus ribeirensis Pilsbry,1911 were collected near the type locality for comparison withthe new cave species (Received 2 December 1993; accepted 20 June 1994)     

A likelihood approach to calculating risk support intervals.

Genetic risks are usually computed under the assumption that genetic parameters, such as the recombination fraction, are known without error. Uncertainty in the estimates of these parameters must translate into uncertainty regarding the risk. To allow for uncertainties in parameter values, one may employ Bayesian techniques or, in a maximum-likelihood framework, construct a support interval (SI) for the risk. Here we have implemented the latter approach. The SI for the risk is based on the SIs of parameters involved in the pedigree likelihood. As an empirical example, the SI for the risk was calculated for probands who are members of chronic spinal muscular atrophy kindreds. In order to evaluate the accuracy of a risk in genetic counseling situations, we advocate that, in addition to a point estimate, an SI for the risk should be calculated.     

Phylogenetic relationships of the garter snakes based on DNA sequence and allozyme variation

We estimated phylogenetic relationships among 26 species of garter snakes (genus Thamnophis ) using allozyme and mitochondrial cytochrome b gene nucleotide sequence variation. Parsimony analyses of the two data sets give substantially different estimates of phylogeny. Several lines of evidence indicate that much of this conflict is due to error associated with the restricted number of characters in each data set. Such sampling error may be reduced by combining all the characters; we therefore present an estimate of phylogeny based on parsimony analysis of all the data combined. All our analyses support several conclusions in conflict with previous views: a very distant relationship between T.errans and T. elegans , non-monophyly of the elegans group (even excluding T: errans ), and nesting of the form validus (previously considered a member of the genus Nerodia ) within Thamnophis.
The combined analysis gives an almost fully resolved tree. However, bootstrapping indicates only weak support for many clades in this tree. Furthermore, paraphyly of the assemblages of cytochrome b gene lineages within T. elegans and T. radix indicate the potential for discordance between the mitochondrial DNA (mtDNA) and species phylogenies through the sorting of ancestral mtDNA polymorphisms. These problems suggest the need for assaying additional characters, especially ones likely to be independent of those used in the present study.     

Pleural Fluid Adenosine Deaminase and Lymphocyte Proportion: Clinical Usefulness In the Diagnosis of Tuberculosis

Adenosine deaminase (ADA) and lymphocyte proportion are known to be independently elevated in tuberculous effusions, but are non-specific, and false positive results are frequent. to overcome this problem the combined use of both parameters was prospectively studied in 276 patients with pleural effusion seen at Porto Alegre, Brazil. Using a cut-off level of 40 U/l at 37°C (method of Giusti¹⁹) for ADA activity and lymphocyte proportion of more than 50%, the correct diagnosis of tuberculosis (sensitivity) was made in 90.7% (CI 87.3–94.1%) of 54 patients. A specificity of 97.7% (CI 95.9–99.5%) was recorded. Five false positive diagnoses of tuberculous effusion were made. Five false negative diagnoses were made: three cases with haematogenous tuberculous dissemination with low ADA levels, and two other patients with low lymphocyte proportion. the combined use of ADA activity determination and lymphocyte proportion is a highly efficient diagnostic strategy of low cost, that merits wider use.     

On Paraptychostomum almae N. G., N. Sp., a Commensal Ciliate from the Digestive Tract of Oligochaetes of the Cameroons, in a New Subclass Hysterocinetia

ABSTRACT. Morphological and ultrastructural studies on a new ciliate, Paraptychostomum almae , from the digestive tract of an oligochaete ( Alma emini ) from the Cameroons are carried out. The flattened cell has a large size; its left lateral face bears an anterior thigmotactic zone that includes seven-nine short kinetal segments. The somatic cortex is composed of flattened alveoli, a thin epiplasm and a microfibrillar ecto-endoplasmic boundary. Kineties are made of monokinetids, each particularly characterized by a long anteriorly directed kinetodesmal fiber, and a hyperdivergent postciliary ribbon. The postero-ventral buccal apparatus consists of a short peristome and a deep longitudinal infundibulum. The paroral organelle is a long stichodyad. The three adoral organelles are of different types: ADI and AD3 are of the membranoid type, respectively with two and one rows of ciliated kinetosomes; AD2 is of the peniculus type with six-seven rows of ciliated kinetosomes. A microfibrillar network with nodes arises from all the buccal kinetosomes and extends under the naked wall. Mitochondria are small and numerous and dispersed throughout the whole cell. The existence of an AD2 with more than two rows of kinetosomes warrants the creation of the new genus Paraptychostomum and a new family, Ptychostomatidae. The presence of a distinct ecto-endoplasmic boundary and of somatic kinetids exclusive without transversal dense tractus, hyperdivergent postciliary ribbons, and dispersed numerous mitochondria, added to particularities of the stomatogenesis, allow us to clearly separate hysterocinetians from the scuticociliates and to set up for them the new subclass Hysterocinetia, within the class Oligohymenophorea, with a single new order Hysterocinetida.