Molecular evidence for deep phylogenetic divergence in Mandrillus sphinx

Mandrills (Mandrillus sphinx) are forest primates indigenous to western central Africa. Phylogenetic analysis of 267 base pairs (bp) of the cytochrome b gene from 53 mandrills of known and 17 of unknown provenance revealed two phylogeographical groups, with haplotypes differentiated by 2.6% comprising seven synonymous transitions. The distribution of the haplotypes suggests that the Ogooué River, Gabon, which bisects their range, separates mandrill populations in Cameroon and northern Gabon from those in southern Gabon. The haplotype distribution is also concordant with that of two known mandrill simian immunodeficiency viruses, suggesting that these two mandrill phylogroups have followed different evolutionary trajectories since separation.     

Fragmented forests, evolving flies: molecular variation in African populations of Drosophila teissieri

Microsatellite variation from eight loci was studied in five populations of Drosophila teissieri, a fruit-fly found only in the rain forests of sub-Saharan Africa. Five noncontiguous rain forest sites (from Tanzania, Gabon and Ivory Coast) were sampled to measure the effects of historical forest fragmentation on population structure in an obligatory forest-dwelling species. The Ivory Coast and Gabon populations showed a wider range of alleles, different modal alleles and had a higher genetic diversity than the three East African populations. As could be expected, genetic differentiation (FST) was significantly correlated with physical distance, but the westernmost population (Ivory Coast) showed values that were intermediate between the central (Gabon) and Eastern (Tanzania) populations. A migration-drift equilibrium in a stable continuum of populations did not appear adequate to describe the observed distribution. It seems probable that the species has undergone abrupt changes involving isolation, merging and migration of populations, as a consequence of repeated waves of forest fragmentation and coalescence.     

Indole alkaloids induction of tremors: effect on photosensible epilepsy in Papiopapio]

Harmaline and ibogaine i.v. administration induced in the photosensitive baboon restlesness and tremor (8-12 Hz). The former increased the EEG frequency particularly in central regions with appearance of bursts at 20-24 c/s and blocked by somatic movement. The latter produced a slight enhancement of frontal fast rhythms. Both drugs blocked the spontaneous paroxysmal activity with little effect on photosensitivity. These effects lasted for 2-4 hrs. Vincamine produced agitation during 15 min. post-i.v.-administration and showed an "hypervigilant" EEG. Nor vincamine or Hydergine altered the degree of photosensitivity. Cerebellar involvement in the action of harmaline and iboga?ne is discussed.     

Effect of Iboga Alkaloids on μ-Opioid Receptor-Coupled G Protein Activation

Objective

The iboga alkaloids are a class of small molecules defined structurally on the basis of a common ibogamine skeleton, some of which modify opioid withdrawal and drug self-administration in humans and preclinical models. These compounds may represent an innovative approach to neurobiological investigation and development of addiction pharmacotherapy. In particular, the use of the prototypic iboga alkaloid ibogaine for opioid detoxification in humans raises the question of whether its effect is mediated by an opioid agonist action, or if it represents alternative and possibly novel mechanism of action. The aim of this study was to independently replicate and extend evidence regarding the activation of μ-opioid receptor (MOR)-related G proteins by iboga alkaloids.

Methods

Ibogaine, its major metabolite noribogaine, and 18-methoxycoronaridine (18-MC), a synthetic congener, were evaluated by agonist-stimulated guanosine-5´-O-(γ-thio)-triphosphate ([³⁵S]GTPγS) binding in cells overexpressing the recombinant MOR, in rat thalamic membranes, and autoradiography in rat brain slices.

Results And Significance

In rat thalamic membranes ibogaine, noribogaine and 18-MC were MOR antagonists with functional Ke values ranging from 3 uM (ibogaine) to 13 uM (noribogaine and 18MC). Noribogaine and 18-MC did not stimulate [³⁵S]GTPγS binding in Chinese hamster ovary cells expressing human or rat MORs, and had only limited partial agonist effects in human embryonic kidney cells expressing mouse MORs. Ibogaine did not did not stimulate [³⁵S]GTPγS binding in any MOR expressing cells. Noribogaine did not stimulate [³⁵S]GTPγS binding in brain slices using autoradiography. An MOR agonist action does not appear to account for the effect of these iboga alkaloids on opioid withdrawal. Taken together with existing evidence that their mechanism of action also differs from that of other non-opioids with clinical effects on opioid tolerance and withdrawal, these findings suggest a novel mechanism of action, and further justify the search for alternative targets of iboga alkaloids.     

Population age structure and reproductive behavior of the monocarpic perennial Heracleum mantegazzianum (Apiaceae) in its native and invaded distribution ranges

Many invasive species are benign in their native region-are there interactions between their key traits and the new habitats that explain invasion success? The giant perennial herb Heracleum mantegazzianum is a problematic invader in Europe and is also naturalized in North America. We compared its population structure and reproductive behavior in the native (W. Caucasus) and invaded (Czech Republic) areas in managed (pastures) and unmanaged sites. The age structure of the populations and age at flowering were analyzed using herb-chronology, a method based on counting annual rings in the secondary xylem of roots. The species was strictly monocarpic; most plants in unmanaged sites in the invaded range flowered in the third and fourth yr (maximum 12 yr). In unmanaged habitats, plants from the native range flowered later than those from the invaded range. In both ranges, flowering was delayed in managed sites where the population density was higher and most plants flowered around the fifth year. Reproductive output of individual plants was neither related to population density nor to age at flowering. More favorable climatic conditions in the invaded region, together with increased chances for dispersal in a densely colonized central Europe, seemed to allow the massive invasion.     

Observations on Schistosoma intercalatum in south-east Gabon

Observations were made in the field and laboratory to determine the strain characteristics of Schistosoma intercalatum in south-east Gabon. For an isolate from Franceville, data are given for egg shape, behaviour of cercariae, seven enzyme systems separated by isoelectric focusing, and intermediate host specificity. Isolates from Cameroun (Edea) and Zaire (Kisangani) were included in a comparative study of the enzymes; Franceville and Edea isolates resembled each other but differed from the Zaire isolate in hexokinase and phosphoglucomutase. The Franceville isolate was polymorphic in phosphoglucomutase and glucosephosphate isomerase. The sum of characters indicates that S. intercalatum as known from south-east Gabon belongs to the strain found in Cameroun and western Gabon, rather than to the strain known from Zaire. More information is needed on strain distribution, particularly for an area including western Zaire and the Republic of the Congo, which appears to separate the two known strains.     

Population Density of Chimpanzees and Gorillas in the Petit Loango Reserve,Gabon: Employing a New Method to Distinguish Between Nests of the Two Species

We studied the vegetation and population density of chimpanzees (Pan troglodytes troglodytes) and gorillas (Gorilla gorilla gorilla) in the Petit Loango Reserve, Gabon. The study site consists mainly of primary and secondary forest, and it also includes patches of savanna, inundated forest, and coastal scrub. The density of herbaceous plants of Marantaceae and Zingiberaceae, which serve as important foods for great apes at other study sites, is extremely low. It was very difficult to distinguish between the nests of chimpanzees and gorillas because most gorilla nests were made in trees. We developed a new method to identify the builder of nests via a combination of field observation of nests and fecal samples, and examination of hair samples under a scanning electron microscope. Nests of chimpanzees were mainly in primary forest, and the estimated density (0.78 individual per km ² ) is higher than the average density in Gabon and comparable to the nest density in the Lopé Reserve, Gabon. Nests of gorillas were mainly in secondary forest, and their estimated density (0.21) is similar to the average next density in Gabon but lower than the gorilla nest density in the Lopé Reserve. The low density of herbaceous foods seemed to influence the density of gorillas but not the density of chimpanzees.     

Occurrence of hepatitis viruses in wild-born non-human primates: a 3 year (1998-2001) epidemiological survey in Gabon

Hepatitis B and C infections are endemic in human population in central Africa, particularly in Gabon. The aim of this study was to determine the prevalence of hepatitis B virus (HBV) and eventual occurrence of hepatitis C virus (HBC)-related strains in a variety of wild-born non-human primates living in Gabon and Congo. Plasma samples were screened for HBV and HCV markers. A non-invasive method of DNA extraction from faeces followed by specific HBV-DNA amplification was developed to study this infection in wild troops of chimpanzees and gorillas. No HCV infection in non-human primates, wild-born or captive, was detected among 596 samples tested. No HBV infection could be detected in samples tested and obtained from Cercopithecidae. In contrast, 14.7 and 42.2% of wild-born chimpanzees in Gabon and Congo were infected with HBV or had evidence of past HBV infection. At Centre International de Recherches Médicales (CIRMF) Primate Centre, 32.1% of chimpanzees and gorillas were HBV positive or had evidence of past infection. In the cases with past infection, 5.9% wild-born and 8.3% at CIRMF harboured HBV-DNA despite the presence of neutralizing HbsAb. Together with previous findings, we confirm the high HBV prevalence not only in humans but also in chimpanzees and gorillas in Gabon and Congo.     

Relatedness and demography of African forest elephants: inferences from noninvasive fecal DNA analyses

African forest elephants (Loxodonta cyclotis) are genetically and morphologically distinct from their savannah counterparts, but their biology remains poorly understood. In this study, I use noninvasive fecal DNA analyses to examine the relatedness structure and historical demography of forest elephants at 2 sites in SW Gabon, central Africa. Pairwise relatedness values calculated between 162 elephant individuals genotyped at 8 microsatellite loci were significantly higher within spatially associated dung piles than between random pairings for one site. First- and second-order relatives were most commonly detected among dung piles from adult female pairs and adult females and juveniles. Pairwise relatedness estimates suggested that, like savannah elephants, forest groups are largely composed of adult females, their sisters, and juvenile offspring. Associations between males, and groups containing juveniles from multiple related females, were detected but at much lower frequency. Analysis of mitochondrial d-loop sequences from 70 elephant individuals identified 2 haplogroups in SW Gabon.     

The African rainforest: odd man out or megafaunal landscape? African and Amazonian forests compared

Africa has been called the ‘odd man out’ because the hectare‐scale tree diversity of African equatorial forests is lower than that of forests in other parts of the tropics. Low diversity has been attributed to the smaller area of the African forest and a history of drought, fire and contraction. Several facts shed doubt on this interpretation. The current area of the central African forest is roughly 2 million km². Even during periods of Pleistocene contraction, numerous moist refugia remained, including 6 posited for Gabon, a country the size of the U. S. state of Colorado. The gamma‐diversity of Gabon is high, implying higher alpha diversities. Finally, tree diversities on small islands in the Solomons and Fiji archipelagos are twice those prevalent in Gabonese forests, suggesting that historical contractions may not have been sufficient to reduce diversity to its current level. To place the African situation in perspective, we compared tree stands in Gabon and the Peruvian Amazon. Peruvian forests contained a mean of 618 trees ≥ 10 cm dbh per ha vs 377 for Gabon, or 64% more. Peruvian forests contained relatively more small trees (≥ 10, <20 cm dbh) and many fewer large trees (≥ 20 cm dbh) than Gabonese forests. These structural differences were consistent across 10 Gabonese and 10 Peruvian sites and transcended local gradients in climate and geology, suggesting that they are intrinsic to the two continents. Tree species diversity in Perú is concentrated in the small tree class (≥ 10, <20 cm dbh), whereas it is highest in the larger tree classes in Gabon. Alpha diversity is apparently lower relative to gamma diversity in Africa than it is in Amazonian Perú , implying higher beta diversity. The densities of small plants (<1 m tall) are similar in Gabonese and Peruvian forests; the observed structural differences develop later at the sapling and small tree stages. Explaining the low hectare‐scale diversity of African forests thus reduces to understanding why the density and diversity of small trees is so anomalously low.     

Occurrence of Glossina nashi Potts 1955 Diptera-Glossinidae in the Republic of Gabon

Glossina nashi, a little known species of tsetse fly, inhabits the forests of central Africa. It has recently been detected in the Province of Haut Ogooué in the south-east of the Republic of Gabon.     

Plant-mycorrhizal fungi feedbacks: potential accomplices of <Emphasis Type="Italic">Avena barbata</Emphasis>’s high invasiveness

Alteration of the soil microbial communities can have important effects on plant invasion. The interdependence between plants and soil microbes could generate complex dynamics in which the composition of plant communities is regulated by the feedbacks of microbial communities on plant growth. In a greenhouse experiment we tested whether the soil microbes in roots of an invasive annual (Avena barbata, wild oat) and a native grass (Rytidosperma caespitosum, wallaby grass) can affect invasive and/or native plant performance. Individuals of each plant species were planted in sterilized soil to which pieces of roots of the same or the other species were added as a layer below the top soil. When plants were harvested after 10 weeks, the addition of roots of any species reduced the total biomass of wild oat. On the other hand, addition of roots of wild oat caused a much stronger reduction of the growth of wallaby grass, while roots of wallaby grass tended to increase its plant growth and shifted biomass allocation patterns. On balance, given the strength of the negative effects, our results indicated that invasion-induced changes in the soil microbial community could contribute to a displacement of the native grass. Thus, these changes might induce a positive feedback mechanism, contributing to the increased dominance of wild oat over wallaby grass in South Australian grasslands.     

Lactate Dehydrogenase in Oryza sativa L. Seedlings and Roots: Identification and Partial Characterization

A lactate dehydrogenase activity is present in rice (Oryza sativa L.) seedlings and roots. Under aerobic conditions, lactate dehydrogenase activity is barely detectable in rice seedlings and is very low in rice roots. In 30 day old roots, the activity is increased two to three times by an anoxic or hypoxic treatment and can be detected on immunoblots by an antiserum raised against barley lactate dehydrogenase. The activity present in aerobic seedlings was partially purified. The native enzyme has a molecular mass of 160 kilodaltons, and is a tetramer of 2 subunit (38 and 39 kilodaltons) randomly associated. Studies of substrate specificity, native gel electrophoresis, and immunoblot analysis indicate that the partially purified enzyme is a typical lactate dehydrogenase. However, no increase of lactate dehydrogenase activity or protein was observed in seedlings transferred to anoxia.     

The Co-occurrence and Morphological Continuum Between Ericoid Mycorrhiza and Dark Septate Endophytes in Roots of Six European Rhododendron Species

Ericaceae associate with a wide spectrum of root mycobionts, but the most common are ascomycetous ericoid mycorrhizal fungi and dark septate endophytes (DSE), followed by basidiomycetous fungi and glomeracean arbuscular mycorrhizal fungi. We investigated distribution and morphological diversity of ericoid mycorrhizae (ErM), DSE associations, ectomycorrhizae (EcM) and arbuscular mycorrhizae (AM) in hair roots of six European native Rhododendron species and found that i) while EcM and AM were absent, ErM and DSE associations were simultaneously present in all screened plants; ii) their levels were negatively correlated, suggesting Ericaceae preference for certain root-fungus association in certain habitats; iii) the highest ErM colonization occurred at sites in southern and central Europe, while the highest DSE colonization was found in a subarctic site in northern Finland and in a subalpine site in the Carpathians, suggesting a latitudinal/altitudinal shift in Ericaceae root-fungus associations; iv) some mycelia could simultaneously form structures corresponding to ErM and DSE association, which occasionally resulted in a unique ectendomycorrhizal colonization comprising an intercellular parenchymatous net and intracellular hyphal coils. These results indicate frequent interactions between ErM fungi and DSE in roots of European rhododendrons and a morphological continuum between ErM and DSE associations. The new ectendomycorrhizal type deserves further investigation.     

New Strain of Simian Immunodeficiency Virus Identified in Wild-Born Chimpanzees from Central Africa

Studies of primate lentiviruses continue to provide information about the evolution of simian immunodeficiency viruses (SIVs) and the origin and emergence of HIV since chimpanzees in west–central Africa (Pan troglodytes troglodytes) were recognized as the reservoir of SIVcpzPtt viruses, which have been related phylogenetically to HIV-1. Using in-house peptide ELISAs to study SIV prevalence, we tested 104 wild-born captive chimpanzees from Gabon and Congo. We identified two new cases of SIVcpz infection in Gabon and characterized a new SIVcpz strain, SIVcpzPtt-Gab4. The complete sequence (9093 bp) was obtained by a PCR-based ‘genome walking’ approach to generate 17 overlapping fragments. Phylogenetic analyses of separated genes (gag, pol-vif and env-nef) showed that SIVcpzPtt-Gab4 is closely related to SIVcpzPtt-Gab1 and SIVcpzPtt-Gab2. No significant variation in viral load was observed during 3 years of follow-up, but a significantly lower CD4+ T cells count was found in infected than in uninfected chimpanzees (p<0.05). No clinical symptoms of SIV infection were observed in the SIV-positive chimpanzees. Further field studies with non-invasive methods are needed to determine the prevalence, geographic distribution, species association, and natural history of SIVcpz strains in the chimpanzee habitat in Gabon.     

Allelopathic effect of Aconitum pendulum (Ranunculaceae) on seed germination and seedlings of five native grass species in the Tibetan Plateau

Aconitum pendulum is a dominant weed in bare‐land meadows on the Tibetan plateau and infected areas are very difficult to restore because of the allelopathic effects of this weed. We wanted to select native grasses to restore bare‐land meadows dominated by this toxic weed and tested the allelopathic effect of A. pendulum on seed germination and growth of roots and shoots of five native forage grasses (Elymus nutans, E. sibiricus, Poa crymophila, Festuca sinensis, Bromus inermis). Leaf exudates and high concentrations of root and stem exudates of A. pendulum inhibited seed germination as well as growth of roots and shoots. The allelopathic effect of A. pendulum leaf exudates was stronger than that of roots and stems. Poa crymophila was most resistant to inhibition by A. pendulum, whereas F. sinensis was the most susceptible grass. We conclude that P. crymophila is more suitable than the other four native grasses for sowing in pastures when restoring bare‐land meadows dominated by A. pendulum in the Tibetan plateau.