Molecular diversity of entodiniomorphid ciliate Troglodytella abrassarti and its coevolution with chimpanzees

The entodiniomorphid ciliate Troglodytella abrassarti is a colonic mutualist of great apes. Its host specificity makes it a suitable model for studies of primate evolution. We explored molecular diversity of T. abrassarti with regard to large geographical distribution and taxonomic diversity of its most common host, the chimpanzee. We found a very low diversification of T. abrassarti in chimpanzees across Africa. Distribution of two types of T. abrassarti supports evolutionary separation of the Western chimpanzee, P. t. verus, from populations in Central and East Africa. Type I T. abrassarti is probably a derived form, which corresponds with the Central African origin of chimpanzees and a founder event leading to P. t. verus. Exclusivity of the respective types of T. abrassarti to Western and Central/Eastern chimpanzees corroborates the difference found between an introduced population of presumed Western chimpanzees on Rubondo Island and an autochthonous population in mainland Tanzania. The identity of T. abrassarti from Nigerian P. t. ellioti and Central African chimpanzees suggests their close evolutionary relationship. Although this contrasts with published mtDNA data, it corroborates current opinion on the exclusive position of P. t. verus within the chimpanzee phylogeny. The type of T. abrassarti occurring in Central and East African common chimpanzee was confirmed also in bonobos. This may point to the presence of an ancestral Type II found throughout the Lower Guinean rainforest dating back to the common Pan ancestor. Alternatively, the molecular uniformity of T. abrassarti may imply a historical overlap of the species' distribution ranges.     

Habitat-specific type I polyketide synthases in soils and street sediments

Actinomycetes produce many pharmaceutically useful compounds through type I polyketide biosynthetic pathways. Soil has traditionally been an important source for these actinomycete-derived pharmaceuticals. As the rate of antibiotic discovery has decreased and the incidence of antibiotic resistance has increased, researchers have looked for alternatives to soil for bioprospecting. Street sediment, where actinomycetes make up a larger fraction of the bacterial population than in soil, is one such alternative environment. To determine if these differences in actinomycetal community structure are reflected in type I polyketide synthases (PKSI) distribution, environmental DNA from soils and street sediments was characterized by sequencing amplicons of PKSI-specific PCR primers. Amplicons covered two domains: the last 80 amino acids of the ketosynthase (KS) domain and the first 240 amino acids of the acyltransferase (AT) domain. One hundred and ninety clones from ten contrasting soils from six regions and nine street sediments from six cities were sequenced. Twenty-five clones from two earthworm-affected samples were also sequenced. UniFrac lineage-specific analysis identified two clades that clustered with actinomycetal GenBank matches that were street sediment-specific, one similar to the PKSI segment of the mycobactin siderophore involved in mycobacterial virulence. A clade of soil-specific sequences clustered with GenBank matches from the ambruticin and jerangolid pathways of Sorangium cellulosum. All three of these clades were found in sites >700 km apart. Street sediments are enriched in actinomycetal PKSIs. Non-actinomycetal PKSI pathways may be more chemically diverse than actinomycetal PKSIs. Common soil and street sediment PKIs are globally distributed.     

The Malagarasi River Does Not Form an Absolute Barrier to Chimpanzee Movement in Western Tanzania

The Malagarasi River has long been thought to be a barrier to chimpanzee movements in western Tanzania. This potential geographic boundary could affect chimpanzee ranging behavior, population connectivity and pathogen transmission, and thus has implications for conservation strategies and government policy. Indeed, based on mitochondrial DNA sequence comparisons it was recently argued that chimpanzees from communities to the north and to the south of the Malagarasi are surprisingly distantly related, suggesting that the river prevents gene flow. To investigate this, we conducted a survey along the Malagarasi River. We found a ford comprised of rocks that researchers could cross on foot. On a trail leading to this ford, we collected 13 fresh fecal samples containing chimpanzee DNA, two of which tested positive for SIVcpz. We also found chimpanzee feces within the riverbed. Taken together, this evidence suggests that the Malagarasi River is not an absolute barrier to chimpanzee movements and communities from the areas to the north and south should be considered a single population. These results have important consequences for our understanding of gene flow, disease dynamics and conservation management.     

MANAGEMENT OF NEPHROSIS—The Use of Long Continued Hormone Therapy

The course of nephrosis in 36 children was evaluated. Twelve of 24 who received no treatment or short-term courses of steroids died. Eleven of the 24 had been well for six months to five years at the time of this report.Twelve patients received steroids by schedule over extended periods. One died and eleven had been free of signs and symptoms of nephrosis for four to eighteen months at the time of report. In only two cases was therapy discontinued. It seems evident that these patients are experiencing a better state of well-being. Whether or not the prognosis is being altered for any single patient cannot be determined.     

A novel Dps-type protein from insect gut bacteria catalyses hydrolysis and synthesis of N-acyl amino acids

A novel type of a microbial N-acyl amino acid hydrolase (AAH) from insect gut bacteria was purified, cloned and functionally characterized. The enzyme was obtained from Microbacterium arborescens SE14 isolated from the foregut of larvae of the generalist herbivore Spodoptera exigua. The substrates of AAH are N-acyl-glutamines previously reported to elicit plant defence reactions after introduction into the leaf during feeding. The isolated AAH catalyses the hydrolysis of the amide bond (K(m) = 36 micromol l(-1)) and, less efficient, the formation (K(m) = 3 mmol l(-1)) of the elicitor active N-acyl amino acids. The AAH from M. arborescens SE14 shows no homology to known fatty acyl amidases (EC 3.5.1.4) but belongs to the family of Dps proteins (DNA-binding protein from starved cell). In line with other DPS proteins AAH is a homododecamer (monomer 17 181 Da) and contains iron atoms (c. 1-16 iron atoms per subunit). Unlike genuine DPS proteins the enzyme does not significantly bind DNA. Amino acid hydrolase is the first member of the DPS family that catalyses the cleavage or formation of amide bonds. The participation of a microbial enzyme in the homeostasis of N-acyl-glutamines in the insect gut adds further complexity to the interaction between plants and their herbivores.     

New solvent-producing Clostridium sp. strains, hydrolyzing a wide range of polysaccharides, are closely related to Clostridium butyricum

Thirteen new Clostridium strains, previously isolated from soil and found to produce high amounts of solvents from glucose, hydrolyzed a great variety of α- and β-glycans, including raw starch, xylan, pectin, inulin and cellulose. The sequences of the PCR-amplified DNA fragments containing the variable 3′ part of one of the 16S rRNA genes were 99.5% identical. The macrorestriction pattern of two endonucleolytic digests of chromosomal DNA in the pulsed-field gel electrophoresis (PFGE) confirmed their high homogeneity on the DNA level. The complete 16S rRNA gene sequence of three selected strains was 99.8% identical to the 16S rRNA gene sequence from Clostridium butyricum and separates them from C. acetobutylicum. To the closely related four species of solventogenic clostridia a new group of strains has to be added, which has a great potential for the direct fermentation of biomass. Journal of Industrial Microbiology & Biotechnology (2001) 27, 329–335. Received 12 September 2000/ Accepted in revised form 25 July 2001