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At least 19 recordsLinked to original sources
PubMed2026

Paleogenomics and habitat modeling reveal temperate Eurasian origins of woolly rhinoceroses.

The woolly rhinoceros was a prominent Ice Age megafaunal species, and there is limited knowledge regarding its origin and responses to past glacial cycles. We sequenced 29 mitochondrial and 14 nuclear genomes from Pleistocene specimens across Eurasia and modeled the species' habitats over the past 500,000 years. Our results suggest that its maternal genetic diversity mainly evolved in temperate Eurasia around 460 thousand to 420 thousand years ago during a prolonged glacial-interglacial transition. We found that a ~170-thousand-year-old East Asian individual was ancestral to all later populations, indicating East Asia as one possible origin of Late Pleistocene ancestry. We also identified the Altai region as a major climatic refugium. These findings highlight the crucial role of temperate Eurasia in the evolution of woolly rhinoceroses and the diversification of cold-adapted megafauna.

Animals↗
PubMed1976

New temperate bacteriophage for Bacillus subtilis, rho 11.

A new temperate bacteriophage, rho11, isolated by J. Hoch, has been characterized. This new phage is very similar to the temperate phage phi3T in size (380 nm), host range, homoimmunity, DNA buoyant density (1.694 g/ml), antigenicity, and molecular weight (around 6.0 X 10(7)) as determined in gels. Like phi3T, rho11 converts thymine auxotrophs to prototrophy at high frequency (250 out of 250 tested). Phage rho11 differs from phi3T in plaque morphology and in the endonuclease R-EcoRI digest pattern. Sixteen of the 20 rho11 DNA fragments have migration patterns corresponding to those of the 21 fragments of phi3T. The close similarities yet clear differences between these phages suggest that the two phages have a common ancestor.

Bacillus subtilis↗
PubMed2026

Annotated genome assemblies of two temperate North American dung beetles, Canthon chalcites and Phanaeus vindex.

Dung beetles serve as cultivators of their natural habitats, improving soil health and functions in both natural and anthropogenic environments. Despite their ecological importance, whole genome sequences for Scarabaeinae are limited. Here, we present the draft annotated genome assemblies for 2 temperate species of North American dung beetles collected from eastern Tennessee: Canthon chalcites and Phanaeus vindex. Both genome assemblies were generated from PacBio long reads and have high completeness, with BUSCO scores of 98.1% and 98.6% for C. chalcites and P. vindex, respectively. For C. chalcites, the BRAKER3 pipeline predicted 12,799 genes, and the gene set was 93.7% complete. For P. vindex, the BRAKER3 predicted 12,252 genes, and the gene set was 94.9% complete. From the annotated gene sets, orthologous protein sequence analyses among C. chalcites, P. vindex, the dung beetle species Onthophagus taurus, and the more evolutionarily distant beetle Tribolium castaneum indicated that there are 260 unique protein clusters for C. chalcites and 210 unique protein clusters for P. vindex. These 2 draft genomes provide valuable data for comparative genomics, evolution, and phylogenic studies for dung beetle species.

Animals↗
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↗
PubMed1978

Purification and characterization of a hyaluronidase associated with a temperate bacteriophage of group A, type 49 streptococci.

Urea treatment of a temperate bacteriophage from a type 49 strain of group A streptococcus (Streptococcus pyogenes) followed by ammonium sulfate fractionation, ion exchange, and affinity chromatography of solubilized proteins provided for the recovery (12%) and purification (44-fold) of the phage-associated hyaluronidase. The molecular weight of the homogeneous, purified enzyme was estimated to be 71,000 by polyacrylamide gel electrophoresis (in the presence of sodium dodecyl sulfate) and 75,000 by gel filtration with Sephacryl S-200. The enzyme has a pH optimum of 5.5, a Vmax of 0.1 absorbance unit/min per microgram of protein, and a Km of 4.8 X 10(-2) mg/ml with umbilical cord hyaluronic acid as substrate. Of the cations tested, calcium and magnesium were the only effectors of the enzyme. The enzyme is a glycoprotein (7.25% carbohydrate) containing glucose, galactose, and glucosamine. Analysis of the amino acid composition revealed a predominance of acidic amino acids and a relatively high content of cysteine. The partial specific volume, estimated from the amino acid and sugar analyses, was 0.725 cm3/g.

Amino Acids↗
PubMed1978

Early-blocked asporogenous mutants of Bacillus subtilis are lysogenized at reduced frequency by temperate bacteriophages.

The establishment of lysogeny in early-blocked asporogenous (Spo-) mutants of Bacillus subtilis 168, which were also defective in the production of antibiotics (Abs-), by temperate phage phi105 or SPO2 was studied. It was found that the frequency of lysogenization of Spo-Abs-mutants was 10 to 20% that of the wild-type bacteria. There was no difference in the efficiency of plating and the burst size of phi105 between wild-type and mutant strains. Phi105 lysogens of mutant strains were as stable as those of the wild type. Several rifampin-resistant mutants defective in the production of antibiotics were isolated. They were also defective in spore formation and lysogenized by phi105 at reduced frequency.

Anti-Bacterial Agents↗
PubMed1977

Characterization of group H streptococcal temperate bacteriophage phi 227.

phi 227, a temperate phage from a group H streptococcus (Streptococcus sanguis), was propagated vegetatively in group H strain Wicky 4-EryR, and its characteristics were determined. A procedure dependent on multiplicity of infection, incubation time, and treatment of crude lysates with diatomaceous earth was found to optimize phage yield, resulting in titers of 1 X 10(10) to 2 X 10(10) PFU/ml. Without prior treatment with diatomaceous earth, subsequent purification procedures (methanol, ammonium sulfate, polyethylene glycol) gave recoveries of less than 1% of crude lysate titers. Adsorption of phi227 to host cells was relatively unaffected by the medium, but calcium (not substituted by magnesium) was required for formation of infectious centers. The phage receptor was present on purified cell walls, resisted trypsin and heat, and was removed ty hydrochloric acid, trichloracetic acid, and hot formamide: however, formamide-extracted material failed to inactivate phage, and the nature of the receptor is unknown. Single-step growth experiments showed a latent period of 39 min and a burst size of 100 PFU/infectious center; results were unaffected by omission of supplemental Ca2+, by supplementation with Mg2, addition of glucose, or changes of pH between 6.35 and 8.0; but increased temperature (40 to 43 degrees C) shortened the latent period and decreased the burst size. The latent period was prolonged in genetically competent host cells and in chemically defined medium; and in the latter, the burst size was smaller. Phage replication was sensitive to those metabolic inhibitors which inhibited the host streptococcus: these included rifampin, fluorodeoxyuridine, hydroxyurea, dihydrostreptomycin, and 6-P-hydroxyphenylazouracil. The data suggest that phi227 does not code for a rifampin-resistant RNA polymerase. However, in a rifampin-resistant host strain, phage replication and lysogen formation were both decreased suggesting that altered host core polymerase had less affinity for (some) promotors on the phi227 template. In transfection, a Ca2+-dependent stabilization step that was inhibited by Mg2+ was demonstrated; transformation was not affected by either Ca2+ or Mg2+, and the site and nature of the stabilization are unknown. More than one molecule of DNA was required for plaque formation. Biophysical characterization showed a type B phage of buoyant density (CsCl) 1.50, containing five proteins and 54.8% DNA. The duplex linear DNA had a molecular weight (calculated from contour length) of 23.2 X 10(6) and a guanine plus cytosine content (calculated from melting point) of 42.3 mol%. Similar characterizations of streptococcal phages, including biophysical data, have not been previously available.

Adsorption↗
PubMed1978

Restriction endonuclease mapping of bacteriophage phi105 and closely related temperate Bacillus subtilis bacteriophages rho10 and rho14.

Cleavage maps of the three similar Bacillus subtilis temperate bacteriophages, phi105, rho10, and rho14, were constructed by partial digestion analysis utilizing the restriction endonuclease EcoRI. Comparison of the topography of these maps indicates that all phage DNAs posses cohesive ends and a number of EcoRI restriction sites; the fragments are conserved, and the estimated base substitution/nucleotide divergence between these phages is 0.03 to 0.07 based on conserved fragments or between 0.03 and 0.11 based on conserved cleavage sites. These lines of evidence indicate that phi105, rho10, and rho14 are closely related. Double-enzyme digestion analysis reveals that rho14 DNA has unique SalGI and BglII restriction sites and phi105 DNA has a unique SalGI restriction site, making these phages possible cloning vectors for B. subtilis.

Bacillus subtilis↗
PubMed1979

The role of temperate bacteriophage SP beta in prophage-mediated interference in Bacillus subtilis.

Virulent bacteriophage phi 1 grows on a variety of Bacillus subtilis strains, mutants of this virus which abortively infect the transformable bacillus. B. subtilis 168, while retaining the ability to productively infect related bacteria have been found. In the present study, we demonstrate that the inability of one such variant, phi 1m, to develop normally in strain 168 is mediated by cryptic prophage SP beta. The latter is a temperate bacteriophage which is carried by B. subtilis 168 and most strains derived from this bacterium. Phi 1 m infection of SP beta lysogens begins with apparently normal adsorption, penetration, and inititaion of virus-directed syntheses. At about the 20th min of the latent period, however, there is an abrupt cessation of nucleic acid synthesis and cellular respiration, accompanied by a change in cell permeability. This course of events can be altered to a permissive infection by mutation in the mpi gene of SP beta, by mutation in the spoOA gene of the host, or by growing SP beta lysogens at high temperature. In addition, we found a second class of phi 1 mutants which abortively infect B. subtilis 168 derivatives even in the absence of the SP beta prophage.

Bacillus subtilis↗
PubMedDate not supplied

[Isolation and general characteristics of a group of Pseudomonas aeruginosa temperate phages].

Eighteen temperate phages were isolated from 38 natural strains of Pseudomonas aeruginosa. The phages belong to five heteroimmune groups according to the ability of lysogenic variants of the strains PAO1 and PAT2 to exclude the growth of the superinfecting phage. Phages of the II and V immunity groups are serologically similar; the remaining phages are not inactivated by antisera against phages B26 (II group) and K1338 (V group). Prophages of the II, IV, and V groups are induced by UV for vegetative growth. Phages belonging to different immunity groups vary in their morphology and particle size as was found by electron microscopy. Phages of the I, II, IV and V groups comprise one morphological type, those of the III group are of another morphological type. Phages of the IV group are not adsorbed on the bacterial mutants resistant to phages of the II and V immunity groups.

Bacteriophages↗
PubMed1978

Transfection with replicating DNA from the temperate Bacillus bacteriophage phi 105 and with T4-ligase treated phi105 DNA: the importance in transfection of being longer than genome-length.

Replicating phage DNA extracted from Bacillus subtilis infected with phage phi 105 has a higher activity in transfection than mature DNA. By heteroduplex analysis it was shown that this DNA contains concatemeric molecules. Concatemers, constructed in vitro by treatment of mature DNA with T4-ligase also have an increased activity in transfection. DNA showing an increased activity in transfection does not have a requirement for more than one molecule per transfection event as is typically found for transfection with mature phi 105 DNA. An explanation is given for this difference suggesting that the structure of the ends of the transfecting molecules play an important role intransfection.

Bacillus subtilis↗
PubMed1979

Restriction-fragment map of the temperate Bacillus subtilis bacteriophage SPO2.

The endonucleases BglI, BglII, EcoRI, SalI, SmaI, and XbaI were used to fragment the phage SPO2 DNA. Electrophoretic analysis using ethidiumbromide agarose gels showed the phage to have nine BglI sites, one BglII site, four EcoRI sites, one SalI site, one SmaI site, and six XbaI sites. Using partial digestions, multiple endonuclease digestion, and autoradiography the fragments were sized and ordered into a circular map of 23 Md. Such an analysis locates the endonuclease sites, indicates which endonucleases are potentially useful in cloning with SPO2, and allows insertions and/or deletions in the SPO2 DNA to be characterized.

Bacillus subtilis↗
PubMed1979

A physical map of the genome of temperate phage phi 3T.

A physical map of the genome of Bacillus subtilis bacteriophage phi 3T was constructed by ordering the fragments produced by cleavage of phi 3T DNA with restriction endonucleases AvaII (2 fragments), BglI (2 fragments), SmaI (3 fragments), BamHI (6 fragments), SalI (7 fragments), AvaI (7 fragments), SacI (12 fragments), PstI (14 fragments), and BglII (26 fragments). Two techniques were used to order the fragments: (1) Sets of previously ordered restriction fragments were isolated and redigested with the endonuclease whose cleavage sites were to be mapped. (2) Fragments located near the ends of the genome or near the ends of other restriction fragments were ordered by treating the DNA with lambda exonuclease prior to restriction endonuclease cleavage. The susceptibility of phi 3T DNA to 15 other restriction endonucleases is also reported.

Bacillus subtilis↗
PubMed1977

Properties of four temperate bacteriophages active on Clostridium perfringens type A.

Four temperature bacteriophages (designated as PF1, PF2, PF3 and PF4) were isolated from lysogenic strains of Clostridium perfringens type A. On the basis of plaque morphology, pH stability, DNase and RNase resistance, buoyant density, one-step growth parameters and electron microscope phage dimensions, it seems that these phages are different and unrelated. Calcium was required for better phage replication. Bacterial strain S107 appears to be the only UV-inducible strain as compared with the other three lysogenic strains. PF2 has a unique pattern of pH stability showing two optima values: one at pH 5 and the second at pH 8-9. Generally, all four phages have a better resistance in acid than in alkaline pH values. The CsC1 equilibrium centrifugation patterns reveal low figures for phage PF1, PF2 and PF3 and show off the fact that PF4 lysates contain two viral particules different with respect to their densities, a property which other determinations failed to demonstrate. Each phage, except PF4, is well characterized by the parameters of the one-step growth cycle.

Bacteriophages↗
PubMed1978

[On the distribution of myxobacteria in the temperate South America (author's transl)].

60 soil samples from Southern Chile, mainly from forests and grassland, yielded six species of myxobacteria. In forest soils Myxococcus coralloides and Myxococcus fulvus occur frequently, in grassland soils Myxococcus coralloides and Archangium gephyra are predominating. Myxococcus virescens, Melittangium lichenicola, and Cytobacter fuscus have been observed rarely. It is pointed out that due to climate factors a high soil acidity causes the low nuber of myxobacter species. A comparison with the number of species in substrates from important plant formations over various climates is given.

Chile↗