Coalescent analysis of mtDNA indicates Pleistocene divergence among three species of howler monkey (Alouatta spp.) and population subdivision within the Atlantic Coastal Forest species, A. guariba

We have used coalescent analysis of mtDNA cytochrome b (cyt b) sequences to estimate times of divergence of three species of Alouatta-A. caraya, A. belzebul, and A. guariba-which are in close geographic proximity. A. caraya is inferred to have diverged from the A. guariba/A. belzebul clade approximately 3.83 million years ago (MYA), with the later pair diverging approximately 1.55 MYA. These dates are much more recent than previous dates based on molecular-clock methods. In addition, analyses of new sequences from the Atlantic Coastal Forest species A. guariba indicate the presence of two distinct haplogroups corresponding to northern and southern populations with both haplogroups occurring in sympatry within Sao Paulo state. The time of divergence of these two haplogroups is estimated to be 1.2 MYA and so follows quite closely after the divergence of A. guariba and A. belzebul. These more recent dates point to the importance of Pleistocene environmental events as important factors in the diversification of A. belzebul and A. guariba. We discuss the diversification of the three Alouatta species in the context of recent models of climatic change and with regard to recent molecular phylogeographic analyses of other animal groups distributed in Brazil.

Pathogenesis II: Fungal responses to host responses: interaction of host cells with fungi

Most of our knowledge concerning the virulence determinants of pathogenic fungi comes from the infected host, mainly from animal models and more recently from in vitro studies with cell cultures. The fungi usually present intra- and/or extracellular host-parasite interfaces, with the parasitism phenomenon dependent on complementary surface molecules. Among living organisms, this has been characterized as a cohabitation event, where the fungus is able to recognize specific host tissues acting as an attractant, creating stable conditions for its survival. Several fungi pathogenic for humans and animals have evolved special strategies to deliver elements to their cellular targets that may be relevant to their pathogenicity. Most of these pathogens express surface factors that mediate binding to host cells either directly or indirectly, in the latter case binding to host adhesion components such as extracellular matrix (ECM) proteins, which act as 'interlinking' molecules. The entry of the pathogen into the host cell is initiated by fungal adherence to the cell surface, which generates an uptake signal that may induce its cytoplasmic internalization. Once this is accomplished, some fungi are able to alter the host cytoskeletal architecture, as manifested by a rearrangement of microtubule and microfilament proteins, and this can also induce epithelial host cells to become apoptotic. It is possible that fungal pathogens induce modulation of different host cell pathways in order to evade host defences and to foster their own proliferation. For a number of pathogens, the ability to bind ECM glycoproteins, the capability of internalization and the induction of apoptosis are considered important factors in virulence. Furthermore, specific recognition between fungal parasites and their host cell targets may be mediated by the interaction of carbohydrate-binding proteins, e.g., lectins on the surface of one type of cell, probably a parasite, that combine with complementary sugars on the surface of host-cell. These interactions supply precise models to study putative adhesins and receptor-containing molecules in the context of the fungus-host interface. The recognition of the host molecules by fungi such as Aspergillus fumigatus, Paracoccidioides brasiliensis and Histoplasma capsulatum, and their molecular mechanisms of adhesion and invasion, are reviewed in this paper.

Evidence that the Ceratobasidium-like white-thread blight and black rot fungal pathogens from persimmon and tea crops in the Brazilian Atlantic Forest agroecosystem are two distinct phylospecies

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Divergence Between Sympatric Rice- and Maize-Infecting Populations of Rhizoctonia solani AG-1 IA from Latin America

The basidiomycetous fungus, Rhizoctonia solani anastomosis group (AG)-1 IA is a major pathogen in Latin America causing sheath blight (SB) of rice Particularly in Venezuela. the fungus also Causes banded leaf and sheath blight (BLSB) oil maize, which is considered all emerging disease problem where maize replaced traditional rice-cropping areas or is now planted in adjacent. fields Our goals in this study Were 10 elucidate (i) the effects of host specialization on gene flow between sympatric and allopatric rice and maize-infecting fungal populations and (ii) the reproductive mode of the fungus, looking for evidence of recombination in total, 375 isolates of R. solani AG1 IA sampled from three sympatric rice and maize fields in Venezuela (Porutuguesa State) and two allopatric rice fields from Colombia (Meta State) and Panama (Chiriqui State) were genotyped Using, 10 microsatellite loci Allopatric populations from Venezuela. Colombia. and Panama were significantly differentiated (Phi(ST), of 0 16 to 0 34). Partitioning of the genetic diversity indicated differentiation between sympatric populations from different host species, with 17% of the total genetic variation distributed between hosts while only 3 to 6% wits distributed geographically among the sympatric Venezuelan Fields We detected symmetrical historical migration between the rice- and the maize-infecting populations from Venezuela Rice- and maize-derived isolates were able to infect built rice and maize but were more aggressive Oil their original hosts, consistent with host specialization. Because the maize- and rice-infecting populations are still cross-pathogenic, we postulate that the genetic differentiation was relatively recent and mediated via a host shift. An isolation with nu.-ration analysis indicated that the maize-infecting population diverged from the rice-infecting population between 40 and 240 years ago Our findings also suggest that maize-infecting Populations have a mainly recombining reproductive system whereas the rice-infecting Populations have a Mixed reproductive system in Latin America

Phylogenetic and evolutionary aspects of Paracoccidioides brasiliensis reveal a long coexistence with animal hosts that explain several biological features of the pathogen

The habitat of the mycelial saprobic form of Paracoccidio ides brasiliensis, which produces the infectious propagula, has not been determined and has proven difficult for mycologists to describe. The fungus has been rarely isolated from the environment, the disease has a prolonged latency period and no outbreaks have been reported. These facts have precluded the adoption of preventive measures to avoid infection. The confirmation of natural infections in nine-banded armadillos (Dasypus novemcinctus) with P. brasiliensis, in high frequency and wide geographic distribution, has opened new avenues for the study and understanding of its ecology. Armadillos belong to the order Xenarthra, which has existed in South America ever since the Paleocene Era (65 million years ago), when the South American subcontinent was still a detached land, before the consolidation of what is now known as the American continent. on the other hand, strong molecular evidence suggests that P. brasiliensis and other dimorphic pathogenic fungi - such as Blastomyces dermatitidis, Coccidioides immitis and Histoplasma capsulatum - belong to the family Onygenaceae sensu Into (order Onygenales, Ascomycota), which appeared around 150 million years ago.P. brasiliensis ecology and relation to its human host are probably linked to the fungal evolutionary past, especially its long coexistence with and adaptation to animal hosts other than Homo sapiens, of earlier origin. Instead of being a blind alley, the meaning of parasitism for dimorphic pathogenic fungi should be considered as an open two-way avenue, in which the fungus may return to the environment, therefore contributing to preserve its teleomorphic (sexual) and anamorphic (asexual) forms in a defined and protected natural habitat. (c) 2006 Elsevier B.V. All rights reserved.

Enzyme production by solid-state fermentation: Application to animal nutrition

Many microorganisms that decompose lignocellulosic material are being studied as producers of enzymes to perform enzymatic hydrolysis of the lignocellulosic material present in residues from the agroindustries. Although the cellulose and hemicellulose present in these materials have their value for feeding cattle, their bioavailability requires breakdown of the bonds with indigestible lignin. Predigestion of such materials with ligninases, xylanases and pectinases (cellulase free) may transform the lignocellulosic substrate into a feed with greater digestibility and higher quality for ruminants.. This review provides an overview of variables to be considered in the utilization of fungal plantdepolymerizing enzymes produced by solid-state fermentation from agricultural production residues in Brazil. (c) 2007 Elsevier B. V. All rights reserved.

Role of TLR-2 and fungal surface antigens on innate immune response against Sporothrix schenckii

Sporotrichosis is an infection caused by the dimorphic fungus Sporothrix schenckii. Toll-like receptors (TLRs) play an important role in immunity, since they bind to pathogen surface antigens and initiate the immune response. However, little is known about the role of TLR-2 and fungal surface antigens in the recognition of S. schenckii and in the subsequent immune response. This study aimed to evaluate the involvement of TLR-2 and fungal surface soluble (SolAg) and lipidic (LipAg) antigens in phagocytosis of S. schenckii and production of immune mediators by macrophages obtained from WT and TLR-2 -/- animals. The results showed that TLR-2-/- animals had had statistical lower percentage of macrophages with internalized yeasts compared to WT. SolAg and LipAg impaired phagocytosis and immunological mediator production for both WT and TLR-2-/-. The absence of TLR-2 led to lower production of the cytokines TNF, IL-1β, IL-12 and IL-10 compared to WT animals. These results suggest a new insight in relation to how the immune system, through TLR-2, recognizes and induces the production of mediators in response to the fungus S. schenckii. Copyright © Informa Healthcare USA, Inc.

Produção de enzimas ligninolíticas por fungos basidiomicetos por fermentação em estado sólido utilizando resíduos sólidos agroindustriais, visando potencial aplicação na produção animal

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Microsatellite analysis supports clonal propagation and reduced divergence of Trypanosoma vivax from asymptomatic to fatally infected livestock in South America compared to West Africa

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Sporothrix schenckii complex biology: environment and fungal pathogenicity

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

The COP9 signalosome counteracts the accumulation of cullin SCF ubiquitin E3 RING ligases during fungal development

Defects in the COP9 signalosome (CSN) impair multicellular development, including embryonic plant or animal death or a block in sexual development of the fungus Aspergillus nidulans. CSN deneddylates cullin-RING ligases (CRLs), which are activated by covalent linkage to ubiquitin-like NEDD8. Deneddylation allows CRL disassembly for subsequent reassembly. An attractive hypothesis is a consecutive order of CRLs for development, which demands repeated cycles of neddylation and deneddylation for reassembling CRLs. Interruption of these cycles could explain developmental blocks caused by csn mutations. This predicts an accumulation of neddylated CRLs exhibiting developmental functions when CSN is dysfunctional. We tested this hypothesis in A. nidulans, which tolerates reduced levels of neddylation for growth. We show that only genes for CRL subunits or neddylation are essential, whereas CSN is primarily required for development. We used functional tagged NEDD8, recruiting all three fungal cullins. Cullins are associated with the CSN1/CsnA subunit when deneddylation is defective. Two CRLs were identified which are specifically involved in differentiation and accumulate during the developmental block. This suggests that an active CSN complex is required to counteract the accumulation of specific CRLs during development.

Comparative EST analysis provides insights into the basal aquatic fungus Blastocladiella emersonii

Abstract Background Blastocladiella emersonii is an aquatic fungus of the Chytridiomycete class, which is at the base of the fungal phylogenetic tree. In this sense, some ancestral characteristics of fungi and animals or fungi and plants could have been retained in this aquatic fungus and lost in members of late-diverging fungal species. To identify in B. emersonii sequences associated with these ancestral characteristics two approaches were followed: (1) a large-scale comparative analysis between putative unigene sequences (uniseqs) from B. emersonii and three databases constructed ad hoc with fungal proteins, animal proteins and plant unigenes deposited in Genbank, and (2) a pairwise comparison between B. emersonii full-length cDNA sequences and their putative orthologues in the ascomycete Neurospora crassa and the basidiomycete Ustilago maydis. Results Comparative analyses of B. emersonii uniseqs with fungi, animal and plant databases through the two approaches mentioned above produced 166 B. emersonii sequences, which were identified as putatively absent from other fungi or not previously described. Through these approaches we found: (1) possible orthologues of genes previously identified as specific to animals and/or plants, and (2) genes conserved in fungi, but with a large difference in divergence rate in B. emersonii. Among these sequences, we observed cDNAs encoding enzymes from coenzyme B12-dependent propionyl-CoA pathway, a metabolic route not previously described in fungi, and validated their expression in Northern blots. Conclusion Using two different approaches involving comparative sequence analyses, we could identify sequences from the early-diverging fungus B. emersonii previously considered specific to animals or plants, and highly divergent sequences from the same fungus relative to other fungi.

Binding of the wheat germ lectin to Cryptococcus neoformans chitooligomers affects multiple mechanisms required for fungal pathogenesis

The principal capsular component of Cryptococcus neoformans, glucuronoxylomannan (GXM), interacts with surface glycans, including chitin-like oligomers. Although the role of GXM in cryptococcal infection has been well explored, there is no information on how chitooligomers affect fungal pathogenesis. In this study, surface chitooligomers of C. neoformans were blocked through the use of the wheat germ lectin (WGA) and the effects on animal pathogenesis, interaction with host cells, fungal growth and capsule formation were analyzed. Treatment of C. neoformans cells with WGA followed by infection of mice delayed mortality relative to animals infected with untreated fungal cells. This observation was associated with reduced brain colonization by lectin-treated cryptococci. Blocking chitooligomers also rendered yeast cells less efficient in their ability to associate with phagocytes. WGA did not affect fungal viability, but inhibited GXM release to the extracellular space and capsule formation. In WGA-treated yeast cells, genes that are involved in capsule formation and GXM traffic had their transcription levels decreased in comparison with untreated cells. Our results suggest that cellular pathways required for capsule formation and pathogenic mechanisms are affected by blocking chitin-derived structures at the cell surface of C. neoformans. Targeting chitooligomers with specific ligands may reveal new therapeutic alternatives to control cryptococcosis.

Widespread phenotypic and genetic divergence along altitudinal gradients in animals

Altitudinal gradients offer valuable study systems to investigate how adap- tive genetic diversity is distributed within and between natural populations and which factors promote or prevent adaptive differentiation. The environ- mental clines along altitudinal gradients tend to be steep relative to the dispersal distance of many organisms, providing an opportunity to study the joint effects of divergent natural selection and gene flow. Temperature is one variable showing consistent altitudinal changes, and altitudinal gradi- ents can therefore provide spatial surrogates for some of the changes antici- pated under climate change. Here, we investigate the extent and patterns of adaptive divergence in animal populations along altitudinal gradients by sur- veying the literature for (i) studies on phenotypic variation assessed under common garden or reciprocal transplant designs and (ii) studies looking for signatures of divergent selection at the molecular level. Phenotypic data show that significant between-population differences are common and taxo- nomically widespread, involving traits such as mass, wing size, tolerance to thermal extremes and melanization. Several lines of evidence suggest that some of the observed differences are adaptively relevant, but rigorous tests of local adaptation or the link between specific phenotypes and fitness are sorely lacking. Evidence for a role of altitudinal adaptation also exists for a number of candidate genes, most prominently haemoglobin, and for anony- mous molecular markers. Novel genomic approaches may provide valuable tools for studying adaptive diversity, also in species that are not amenable to experimentation.

Hepatic fungal infection in a young beagle with unrecognised hereditary cobalamin deficiency (Imerslund-Gräsbeck syndrome)

A 12-month-old beagle presented for anorexia, pyrexia and vomiting. The dog had been treated intermittently with antibiotics and corticosteroids for inappetence and lethargy since five months of age. Previous laboratory abnormalities included macrocytosis and neutropenia. At presentation, the dog was lethargic, febrile and thin. Laboratory examination findings included anaemia, a left shift, thrombocytopenia, hypoglycaemia and hyperbilirubinaemia. Multiple, small, hypoechoic, round hepatic lesions were observed on abdominal ultrasound. Cytological examination of hepatic fine needle aspirates revealed a fungal infection and associated pyogranulomatous inflammation. The dog's general condition deteriorated despite supportive measures and treatment with fluconazole, and owners opted for euthanasia before hypocobalaminaemia was identified. Subsequent genomic analysis revealed a CUBN:c.786delC mutation in a homozygous state, confirming hereditary cobalamin malabsorption (Imerslund-Gräsbeck syndrome). Similar to human infants, dogs with Imerslund-Gräsbeck syndrome may rarely be presented for infectious diseases, distracting focus from the underlying primary disorder.