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PubMed1992

Feeding ecology of Saguinus bicolor bicolor (Callitrichidae: Primates) in a relict forest in Manaus, Brazilian Amazonia.

This study is part of a long-term ecological study of habitat and dietary requirements of the pied bare-face tamarin (Saguinus bicolor bicolor). One group was studied for 11 months in an area of secondary forest in a suburb of Manaus, Amazonas, Brazil. Three main vegetation types occurred inside the group's home range (12 ha): capoeira, older secondary forest and campinarana (white sand forest). The tamarins ate fruits (21 species), flowers (1 species), exudates (4 species), and arthropods (insects and spiders). They spent 14.3% of total activity time seeking and eating animal prey, and 9.9% feeding on plant material, mostly fruits. In general, fruits consumed were ripe, small and succulent. Trees used for feeding were low and had small crown diameters. Three plant species (Protium aracouchinni, Myrcia cf. fallax, and Couma utilis) were used intensively during the three seasons covered by the study period. The concentrated use of 3 fruit species, each for an extended period (one fruiting species per season), provided the tamarins with a regular food supply. Tamarins consumed exudates from holes in the bark of trees of the families Anacardiaceae and Vochysiaceae, as well as gum exuded from seed pods of Mimosaceae. Exudates were exploited during the dry season and at the beginning of the wet season. Group travel was primarily based on routes connecting the fruiting trees exploited, with foraging for animal prey occurring during travel. Tamarins searched for arthropods on trunks, branches and leaves and in trunk holes. The foraging and feeding tactics displayed by S. b. bicolor are closely linked to morphological characteristics (small size and weight, claw-like nails) that allowed access to energy-rich resources (arthropods and plant exudates) in different strata of the vegetation.

Animals↗

PubMed1979

Cadmium in forest ecosystems around lead smelters in Missouri.

The development of Missouri's new lead belt within the past decase has provided an excellent opportunity to study the dissemination and effects of heavy metals in a deciduous forest ecosystem. Primary lead smelters within the new lead belt have been identified as potential sources of cadmium as well as lead, zinc, and copper. Sintering and blast furnace operations tend to produce significant quantities of small particulates highly enriched in cadmium and other heavy metals. At one smelter, samples of stack particulate emissions indicate that as ms accompanied by 0.44 lb zinc, 4.66 lb lead, and 0.01 lb copper/hr. These point-source emissions, as well as a number of other sources of fugitive (wind blown) and waterborne emissions contribute to a significant deposition of cadmium in the surrounding forest and stream beds. Mobilization of vagrant heavy metals may be significantly increased by contact of baghouse dusts or scrubber slurries with acidic effluents emanating from acid plants designed to produce H2SO4 as a smelter by-product. Two separate drainage forks within the Crooked Creek watershed permit some comparisons of the relative contributions of cadmium by air-borne versus water-borne contaminants. Cadmium and other heavy metals have been found to accumulate in the forest litter and partially decomposed litter along stream beds. Greater solubility, lower levels of complexation with organic ligands in the litter, and greater overall mobility of cadmium compared with lead, zinc, and copper result in appreciable contributions of dissolved cadmium to the watershed runoff. The present paper attempts to define the principle sources and current levels of heavy metal contamination and summarizes the efforts undertaken by the industry to curtail the problem.

Air Pollutants↗

PubMed1979

[Sudan-savanna and rain-forest onchocerciasis in West Africa: an epidemiological problem (author's transl)].

A Sudan-savanna and a rain forest onchocerciasis have been described in West Africa. These two patterns of onchocerciasis have in common many epidemiological features but in hyperendemic areas there is a very essential difference between the two. In savanna the prevalence of serious ocular lesions and blindness due to onchocerciasis are much higher than in forest. Therefore attempting to explain these differences five groups of factors (or working hypothesis) are reviewed: --factors related to the vectors; --onchocerca-simulium couples; --different Onchocerca volvulus strains; --factors related to the human-host; --other varied factors: nutritional factors, concomitant ocular infections, luminousness of savanna, periods of transmission... A critical examination of these hypothesis brings to the conclusion that according to our present knowledge the main difference between savanna and rain-forest onchocerciasis may be due to degrees in pathogenicity of different strains of O. volvulus but these hypothesis have not been proved formally. More the part of concomitant factors (co-factors), themselves related to bioclimactic zones must not be ruled out.

Adolescent↗

PubMed2025

Landscape heterogeneity, forest structure, and mammalian host diversity shape tick density and prevalence of the causative agent of Lyme borreliosis.

Ticks, particularly Ixodes ricinus, and the associated Lyme borreliosis risk, represent key concerns within the One Health framework, prompting extensive research in this field. However, comprehensive studies that jointly consider landscape characteristics, local forest structure and management, climate, and host community composition-alongside direct measures of tick density and infection status with Borrelia spp., the bacterial agents causing Lyme borreliosis, are scarce. In this study, we test the hypothesis that habitat diversity exerts a dilution effect, primarily by supporting greater diversity of mammal hosts. Therefore, we examined I. ricinus tick density and Borrelia spp. prevalence in relation to a comprehensive set of habitat and host-related variables. Ticks were collected using the flagging method and mammal hosts were monitored using an innovative camera-trapping approach across 25 forest plots along a land-use gradient within the Schwäbische Alb exploratory in Germany. Both tick density and Borrelia spp. prevalence are influenced by a complex combination of habitat factors across different spatial scales, as well as the mammal host community composition. Overall, our results provide novel support to the dilution effect hypothesis, suggesting that greater habitat and host diversity contribute to a reduced Lyme borreliosis risk in this region.

Animals↗

PubMed1976

Serum glycoprotein-type sequence of monosaccharides in membrane glycoproteins of Semliki Forest virus.

Semliki Forest virus was grown in BHK-21 cells and labelled in vivo with radioactive monosaccharides. The virus was disrupted with sodium dodecyl sulphate and the polypeptides were hydrolyzed with pronase. A mixture of type A glycopeptides (for nomenclature, see Johnson and Clamp (1971) Biochem. J. 123, 739-745) of the membrane glycoproteins E1 and E3 was isolated by gel filtration and subjected to sequential degradation with exo-glycosidases. The reduction in the apparent molecular weight and the cleavage of radioactive monosaccharides were monitored with gel filtration. The results suggest that the type A oligosaccharides have similar average structures and contain at the non-reducing terminus 3.4 mol of alpha-D-sialic acid and 0.7 mol of alpha-L-focose, folloled by 3.1 mol of beta-D-galactose, 4.2 mol of N-acetyl-beta-D-glucosamine, 0.7-1.5 mol of alpha-D-mannose, 0.5 mol of beta-D-mannose and 0.6-2.2 mol of N-acetyl-beta-D-glucosamine attached to 1.0 mol of N-acetylglucosamine resistant to N-acetyl-beta-D-glucosaminidase. This innermost monosaccharide unit, therefore, appears to be attached to the peptide. The peptides attached to this N-acetyl-glucosamine had an apparent molecular weight of 720+/-100. We propose the following average structure, compatible with most of our data, for the type A glycopeptides of Semliki Forest virus:.

Animals↗

PubMed1976

Phospholipids of Semliki Forest virus grown in cultured mosquito cells.

The phospholipids of Semliki Forest virus grown in mosquito cells (Aedes albopictus) were analyzed radiochemically. The ratio of 32P-labeled phospholipids to total 32P-label in the virus grown in mosquito cells equilibrated with radiophosphorus was 0.558 +/- 0.021. This value was similar to the lipid phosphorus: total phosphorus ratio (0.539 +/- 0.025) of the virus grown in the BHK cells. It is concluded that an average virion of the two types of Semliki Forest virus contains approximately the same number of phospholipid molecules. Phosphatidylethanolamine (62%), phosphatidylcholine (14%), phosphatidylserine (10%) and the ethanolamine analogue of sphingomyelin, ceramide phosphoethanolamine (9%) were the principal phospholipids in the mosquito cell-grown virus. Comparison with the lipids of virus grown in hamster cells (BHK cells) revealed that two-thirds of the polar structures were dissimilar. Surface labeling with formylmethionyl [35S] sulfone methylphosphate suggests that a relatively large fraction of ceramide phosphoethanolamine is located in the outer half of the lipid bilayer of the viral membrane.

Aedes↗

PubMed1976

Sequential translation of nonstructural proteins in cells infected with a Semliki Forest virus mutant.

Four nonstructural proteins with apparent molecular weights of 70,000 (ns-70), 86,000 (ns-86), 78,000 (ns-78), and 60,000 (ns-60) were translated in cells infected with Semliki Forest virus ts-1 mutant and maintained at the restrictive temperature. After synchronization of the initiation of protein synthesis these proteins were synthesized in the above order, suggesting that they are translated as a polyprotein starting from one initiation site. Two short-lived intermediates with apparent molecular weights of 155,000 and 135,000 were regularly detected. The former is presumably the precursor of proteins ns-70 and ns-86 and the latter of ns-78 and ns-60. The sequence of the structural proteins in their polyprotein was confirmed to be capsid-envelope E-2 (and E-3)-envelope E-1, beginning from the NH2-terminal end. We conclude that in Semliki-Forest-virus-infected cells two polyproteins are synthesized, one for the structural (130,000 daltons), the other for the nonstructural proteins (close to 300,000 daltons).

Mutation↗

PubMed1978

Human (HLA-A and HLA-B) and murine (H-2K and H-2D) histocompatibility antigens are cell surface receptors for Semliki Forest virus.

The proteins coded for by the HLA-A and HLA-B loci in man and the H-2K and H-2D loci in mice were identified as cell surface receptors for Semliki Forest virus. This conclusion is based on the following observations: (i) Water-soluble octamers of viral coat proteins inhibit the complement-dependent cytotoxicity of antibodies directed against H-2K and H-2D antigens in mouse cells. (ii) Isolated detergent-soluble HLA-A and HLA-B antigens reconstituted in lipid vesicles inhibit the binding of viral proteins to human cells (as do the water-soluble antigens to a lesser extent). (iii) Reconstituted HLA-A and HLA-B vesicles interact in solution with Semliki Forest virus (or with vesicles containing viral spike proteins), as demonstrated by coprecipitation with antisera. (iv) Complexes between viral spoke proteins and HLA-A and HLA-B antigens or H-2K and H-2D antigens can be isolated from the cell surface by utilizing affinity chromatography or immunoprecipitation.

Animals↗

PubMed2026

Antimicrobial resistance analysis of Klebsiella pneumoniae bloodstream infections based on a random forest algorithm: a longitudinal study based on data from tertiary hospitals in China from 2012 to 2023.

BACKGROUND: Bloodstream infections (BSIs) caused by Klebsiella pneumoniae pose a significant global health burden, complicated by rising antimicrobial resistance (AMR). This study aimed to characterize resistance patterns, identify predictors of carbapenem resistance, and develop a machine learning model to predict patient outcomes. METHODS: In a retrospective analysis of 109 279 K. pneumoniae BSIs from tertiary hospitals in China (2012-2023), 11 000 isolates underwent whole-genome sequencing (WGS) and antimicrobial susceptibility testing. Cox proportional hazards and logistic regression models identified predictors of 30-day mortality and carbapenem-resistant K. pneumoniae (CRKP), respectively. A random forest model predicted AMR trends and outcomes, evaluated by accuracy, precision, recall, and ROC-AUC using R Studio (R Studio, Inc., Boston, MA, USA). RESULTS: Carbapenem resistance occurred in 32.3% of isolates, with rates of 41.9% for third-generation cephalosporins and 41.2% for fluoroquinolones. Among sequenced isolates, ST11 with blaKPC was the dominant CRKP genotype (12.0%). blaKPC (OR 3.97, 95% CI 3.10-5.11) and blaNDM (OR 2.80, 95% CI 2.07-3.71) strongly predicted carbapenem resistance; ICU admission predicted 30-day mortality (HR 2.10, 95% CI 1.80-2.46, p<0.001). Mortality was higher in CRKP (40.2%) vs. susceptible cases (21.5%). The random forest model achieved 89.2% accuracy and 0.92 ROC-AUC, with drug share, age, and CRKP status as top predictors. CONCLUSIONS: CRKP, especially ST11-blaKPC, drives excess mortality. Key predictors highlight the urgency for enhanced AMR surveillance and targeted therapy.

Humans↗

PubMed1975

Virus development in enucleate cells: echovirus, poliovirus, pseudorabies virus, reovirus, respiratory syncytial virus and Semliki Forest virus.

A group of RNA viruses, echovirus, poliovirus, reovirus, respiratory syncytial virus and Semliki Forest virus have been examined for ability to grow in enucleate African green monkey kidney (BSCi) cells. Semliki Forest virus produced an almost normal yield of virus but poliovirus, echovirus, reovirus and respiratory syncytial virus, although showing clear evidence of virus replication when compared with a nuclear DNA virus (pseudorabies virus) gave much lower yields than those from nucleate cells. Analysis of enucleate cells infected with echovirus and reovirus showed no evidence of a specific block in the synthesis of any virus-specified polypeptide. Infection with vesicular stomatitis virus at intervals after enucleation demonstrated a diminishing ability to support virus growth with increasing time. It is suggested that the yield of virus obtained from an enucleate cell is related to the length of the growth cycle of the virus, the reduced yield obtained with some viruses reflecting the declining ability of the enucleate cell to support virus growth.

Autoradiography↗

PubMed1976

Defective-interfering particles of Semliki Forest virus: intracellular events during interference.

Purified defective-interfering (DI) particles of Semliki Forest virus are unable to carry out any of the steps in virus multiplication except uncoating. Cells co-infected with DI particles and standard virus contain several virus-specified RNA species (DI particle-specific species) absent from cells infected with standard virus alone. Moreover, synthesis of all the virus-specified components distinctive of standard virus-infected cells is reduced. The DI particle-specific RNA species comprise two poly A-containing single-stranded RNAs (DIss1 and DIss2), identical to those found in purified DI particles, two double-stranded RNA'S (RFs) and a new size class of replicative intermediate (RI). Hybridization experiments showed that the nucleotide sequences of DIss1 and DIss2 (i) are present in the 42S genome of standard virus but absent from the 26S RNA- the RNA from standard virus-infected cells which encodes the structural proteins of the virion (Clegg & Kennedy, 1975 a) and (ii) are complementary to the negative strands of the DI paritcle-specific RFs and RI. Oligonucleotide fingerprinting revealed extensive nucleotide sequence homology between DIssI and DIss2. Analysis of the mRNA complement of standard virus-infected, co-infected and uninfected cells strongly indicated that neither DIss1 nor DIss2 can serve as a functional messenger RNA. From these studies we propose a mechanism for the multiplication of and interference by DI particles of Semliki Forest virus.

Base Sequence↗

PubMed1979

Sequence analysis of lactosamine type glycans of individual membrane proteins of Semliki Forest virus.

3H-fucose and 14C-glucosamine labelled glycopeptides of the individual membrane proteins E1, E2 and E3 of Semliki Forest virus could be sequentially digested with alpha-neuraminidase, beta-galactosidase, N-acetyl-beta-glucosaminidase, alpha- and beta-mannosidase, N-acetyl-beta-hexosaminidase and finally with alpha-fucosidase. The degradations of the virus glycopeptides proceeded in the same way as stepwise digestions of reference glycopeptides of the lactosamine type obtained from IgG and alpha 1-acid glycoprotein. This suggests that all three membrane glycoproteins of Semliki Forest virus contained glycans with a monosaccharide sequence characteristic for lactosamine type oligosaccharides. The number of both distal and proximal N-acetyl-glucosamine residues was estimated to be usually two. According to exo- and endo-glycosidase digestions, fucose seemed to be attached to the innermost N-acetyl-glucosamine unit.

Acetylglucosamine↗

PubMed2026

Long-Term Warming Reduces Bacterial Diversity and Functional Potential in Temperate Forest Soil.

Soil microbes are key regulators of forest carbon cycling, yet how their diversity and functional potential respond to long-term warming remains poorly understood. Here, we report a five-year in situ warming experiment in a temperate forest, combining ten repeated measurements of microbial diversity and functional gene potential, as well as continuous monitoring of soil CO2 flux. We found that warming progressively reduced bacterial diversity and induced phylogenetically conserved community reorganization. Under warming, community composition shifted in a phylogenetically conserved manner. Warming generally reduced the abundance of microbial functional genes across most carbon-, nitrogen-, and phosphorus-cycling gene categories, except for genes associated with starch decomposition. Warming also altered the factors associated with soil CO2 flux: microbial diversity showed a stronger association with soil CO2 flux under long-term warming, whereas soil moisture was the dominant predictor in the control treatment. This warming-enhanced biodiversity control over soil CO2 flux was associated with shifts in microbial functional potential, particularly increases in starch-degrading genes and microbial biomass production potential. Together, our results suggest that warming can restructure microbial communities in ways that strengthen biodiversity-dependent regulation of soil carbon cycling, with implications for climate-carbon feedbacks.

Soil Microbiology↗

PubMed1976

Simultaneous translation of structural and nonstructural proteins from Semliki-forest-virus RNA in two eukaryotic systems in vitro.

The Semliki Forest virus genome, 42-S RNA, and the virus-specific intracellular 26-S RNA were translated in two cell-free protein-synthesising systems, the wheat germ extract, and a partially purified system from mammalian tissues. The 26-S RNA directed the synthesis of structual proteins only, as revealed by tryptic peptide mapping. About 75--80% of the radioactivity in the products comigrated with capsid and about 4--8% with envelope protein peptides. All the capsid peptides and the full-sized capsid protein were found in the products in vitro, no complete envelope protein was formed and fewer than half of the envelope peptides were detected. This result is consistent with reports that there is only one initiation site for the translation of virus structural proteins, and that the capsid protein is N-terminal in the polyprotein followed by envelope proteins. The systems programmed with 42-S RNA yielded virtually the same structural peptides. However, the bulk of the radioactivity was in peptides which did not comigrate with the structural ones. These peptides were mostly associated with relatively small-sized products. This shows that Semliki Forest virus 42-S RNA has at least two initiation sites, one for the structural proteins and the other(s) for the nonstructural proteins.

Cell Line↗

PubMed2026

Protecting tropical forests is more cost-effective for biodiversity and climate than restoration.

Halting deforestation and promoting restoration are at the core of strategies to confront the biodiversity and climate crises in tropical forests. Avoiding forest disturbances is also critically important but has received far less attention, and there is a lack of clarity about the relative cost-effectiveness of these three interventions. We compare the biodiversity and carbon benefits and costs associated with each intervention, comparing observed and counterfactual outcomes based on in-depth field assessments and high-resolution remote sensing in the Brazilian Amazon deforestation frontier. Avoidance interventions delivered the greatest benefits and were more cost-effective than restoration, with results being robust to a range of benefit and cost assumptions. However, combined interventions delivered the greatest gains and were essential to reverse biodiversity and carbon losses.

Biodiversity↗

PubMed1977

Brain lysosomal glycosidase activity in immunosuppressed mice infected with avirulent Semliki forest virus.

Mice infected with an avirulent strain of Semliki forest virus show an increase in the activity of some of the brain lysosomal glycosidases. The increase in activity of these enzymes has been correlated with the histological, virological, and serological changes that result from the infection in the presence and absence of immunosuppression. Semliki forest virus alone caused the development of a mild encephalitis with perivascular infiltration, microgliosis, astrocyte hypertrophy, and a focal spongiform encephalopathy, together with an increased activity of brain N-acetyl-beta-D-glucosaminidase and beta-glucuronidase. Antilymphocyte serum given after infection marginally affected the course of the disease. Cyclophosphamide markedly delayed the development of the spongy changes in the increase in enzyme activities, but not the perivascular infiltration. It is suggested that the increased activity of the lysosomal glycosidases studied may be linked both to the development of a successful immune response and to the focal spongiform changes produced by the infection.

Acetylglucosaminidase↗

PubMed1979

Cellular immunity against Semliki Forest virus in mice.

Intracutaneous immunization of BALB/c mice with purified inactivated Semliki Forest virus resulted in cellular immunity without detectable antibodies. The animals were protected against subcutaneous challenge, from which the challenge virus spreads slowly. After intraperitoneal challenge, which permits a rapid virus spread, the protection was marginal. Stimulation of the intraperitoneal cell population with thioglycolate before challenge resulted in complete protection. The protection could be transferred to normal mice with peripheral lymph node cells, but not with spleen cells. The course of the infection in immunized and normal mice was also studied. Semliki Forest virus does not multiply in peritoneal cells in vivo. In immunized mice part of the challenge virus in the peritoneal cavity was rapidly eliminated and viremia was reduced. After challenge, immunized mice produced less antibody than normal mice.

Animals↗

PubMed1975

Tryptic peptide analysis on nonstructural and structural precursor proteins from Semliki Forest virus mutant-infected cells.

Analysis of [35S]methionine-labeled tryptic peptides of the large proteins induced by temperature-sensitive mutants of Semliki Forest virus was carried out. The 130,000-molecular-weight protein induced by ts-2 and ts-3 mutants contained the peptides of capsid protein and of both major envelope proteins E1 and E2. The ts-3-induced protein with molecular weight of 97,000 contained peptides of the capsid and envelope protein E2 but not those of E1. Two proteins with molecular weights of 78,000 and 86,000 from ts-1-infected cells did not contain the peptides of the virion structural proteins. They are evidently expressions of the nonstructural part of the 42S RNA genome of Semliki Forest virus.

Autoradiography↗