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PubMed1999

The responsive C and N biogeochemistry of the temperate forest floor.

Soil organic matter is often viewed as comprising large pools of carbon and nitrogen with long residence times. However, the organic horizon that lies on the soil surface in temperate forests is a dynamic component of ecosystem carbon and nitrogen cycling. Responses to elevated inputs of nitrogen in this organic layer are emerging as key facets of ecosystem retention or loss of dissolved nitrogen. Research along nitrogen deposition gradients in the USA and Europe reveals a link between the ratio of organic carbon:nitrogen in the forest floor and nitrogen turnover rates, nitrification and leaching losses. Characteristics and processes in the forest floor are now recognized as key indicators or determinants of ecosystem 'nitrogen status'.

Journal Article↗
PubMed2002

Gaseous carbon dioxide and methane, as well as dissolved organic carbon losses from a small temperate wetland under a changing climate.

Temperate forests can contain large numbers of wetlands located in areas of low relief and poor drainage. These wetlands can make a large contribution to the dissolved organic carbon (DOC) load of streams and rivers draining the forests, as well as the exchange of methane (CH4) and carbon dioxide (CO2) with the atmosphere. We studied the carbon budget of a small wetland, located in Kejimkujik National Park, Nova Scotia, Canada. The study wetland was the Pine Marten Brook site, a poor fen draining a mixed hardwood-softwood forest. We studied the loss of DOC from the wetland via the outlet stream from 1990 to 1999 and related this to climatic and hydrologic variables. We added the DOC export information to information from a previously published model describing CH4 and CO2 fluxes from the wetland as a function of precipitation and temperature, and generated a new synthesis of the major C losses from the wetland. We show that current annual C losses from this wetland amount to 0.6% of its total C mass. We then predicted that under climate changes caused by a doubling of atmospheric CO2 expected between 2040 and 2050, total C loss from the wetland will almost double to 1.1% of total biomass. This may convert this wetland from what we assume is currently a passive C storage area to an active source of greenhouse gases.

Carbon↗
PubMed1999

Current concerns about control programs in temperate climates.

Efforts to control cyathostome nematodes in temperate climates have not been uniformly successful, as evidenced by contemporary reports of clinical disease and widespread anthelmintic failure. Indeed, effective control is confounded by numerous factors, including ignorance of local transmission patterns, confusing or conflicting control recommendations, and use of ineffective anthelmintics or regimens. Most of these problems are universal rather than being climatically unique, and it is important to recognize that they are mere symptoms of larger and more comprehensive problems. The most basic problem in managing cyathostomes is inadequate knowledge of biological factors that influence control recommendations. These include population dynamics, arrested development, host resistance, and regional bionomics. Another hindrance is the absence of objective criteria to define effective control. Target fecal egg counts are arbitrary and subjective, and parameters to measure the subclinical impact of cyathostome infection in well-managed horses have not been identified. The final general challenge to effective parasite control is motivation and education of equine practitioners and horse owners, who currently receive much of their parasite control information in the form of biased advertising. Ultimately, more effective equine parasite control will result from collaborative efforts of basic research, clinical application, and improved information transfer.

Animals↗
PubMed2001

The role of lipophilic and polar flavonoids in the classification of temperate members of the Anthemideae.

Lipophilic and vacuolar flavonoids were separately identified in representative temperate species of the genera Anthemis, Chrysanthemum, Cotula, Ismelia, Leucanthemum and Tripleurospermum. The four Anthemis species investigated variously produced four main surface constituents, in leaf and flower: santin, quercetagetin 3,6,3'-trimethyl ether, scutellarein 6,4'-dimethyl ether and 6-hydroxyluteolin 6,3'-dimethyl ether. By contrast, surface extracts of disc and ray florets of the species of Chrysanthemum, Cotula, Ismelia, Leucanthemum and Tripleurospermum surveyed yielded five common flavones in the free state: apigenin, luteolin, acacetin, apigenin 7-methyl ether and chrysoeriol. Polar flavonoids were isolated and identified in leaf, ray floret and disc floret of all the above plants. Anthemis species were distinctive in having flavonol glycosides in the leaves, whereas the leaf flavonoids of the other taxa were generally flavone O-glycosides. The 3-glucoside and 3-rutinoside of patuletin were characterised for the first time from Anthemis tinctoria ssp. subtinctoria. Two new flavonol glycosides, the 5-glucuronides of quercetin and kaempferol, were obtained from the leaf of Leucanthemum vulgare, where they co-occur with the related 5-glucosides and with several flavone glycosides. The ray florets of these Anthemideae generally contain apigenin and/or luteolin 7-glucoside and 7-glucuronide, whereas disc florets have additional flavonol glycosides, notably the 7-glucosides of quercetin and patuletin and the 7-glucuronide of quercetin. A comparison of the flavonoid pattern encountered here with those previously recorded for Tanacetum indicate some chemical affinity between Anthemis and Tanacetum. Flavonoid patterns of the other five genera are more distinct from those of Tanacetum and suggest that those genera form a related group. All 14 species surveyed for their flavonoid profiles have distinctive constituents and the chemical data are in harmony with modern taxonomic treatments of the "Chrysanthemum complex" as a series of separate genera.

Journal Article↗
PubMed2003

Molecular and biochemical analysis of the system regulating the lytic/lysogenic cycle in the pneumococcal temperate phage MM1.

The temperate phage MM1 forms stable lysogens in Streptococcus pneumoniae. We report here the first characterization of the lysogenic control region in Pneumococcus which contains two functional divergent promoters (P(R) and P(L)). MM1 encodes a 14-kDa cI protein (CI) that appears to be responsible for maintaining the lysogenic state in Pneumococcus since it prevents elongation of the transcripts controlled by P(R) and P(L).

Bacteriophages↗
PubMed1997

Identification and sequence analysis of the region encoding the site-specific integration system from Leuconostoc oenos (OEnococcus oeni) temperate bacteriophage phi 10MC.

Malolactic fermentation conducted by Leuconostoc oenos is an essential step in winemaking. L. oenos bacteriophages are thought to be responsible for fermentation failures, yet they have received little attention. The integration system of bacteriophage phi 10MC in the LOF111 L. oenos strain chromosome was studied and a 1,456 bp phage DNA fragment was cloned and sequenced. An open reading frame (int) showing homology with several temperate bacteriophage integrases was located upstream of the phage attachment site (attP). This organisation is comparable to other phage site-specific recombination systems. The same bacterial attachment site (attB) located in at tRNA(leu) gene was found in all 15 L. oenos strains studied and was involved in phi 10MC integration in the bacterial chromosome.

Amino Acid Sequence↗
PubMed2002

Comparative analysis of the genomes of the temperate bacteriophages phi 11, phi 12 and phi 13 of Staphylococcus aureus 8325.

The genomes of the three temperate bacteriophages contained in the chromosome of Staphylococcus aureus 8325 have been extracted from the sequence database and analyzed. phi 11, phi 12 and phi 13 are members of the same lytic group but different serogroups and consequently co-habitate the same host cell. Their genomes are approximately 42 kb to 45 kb and contain about 90 ORFs of at least 50 codons. Of these, about 50 have similarities to known genes or to genes of other staphylococcal phages. Each of the phages clusters within a homology group that share large regions of sequence identity while intergroup homology is comparatively low. The arrangement of genes on the chromosomes of the three phages is similar and consistent with current modular theory of phage gene organization. The replicated genomes appear to be packaged by different mechanisms. Phage phi 11 and phi 12 have been found to contain sequences consistent with pac-site phages while phi 13 has sequences consistent with cos-site phages. The attBsite for phi 11 is located in an intergenic region of the S. aureus chromosome while phi 12 and phi 13 integrate into specific genes. The phi 12 att-site is within an unknown gene, but the phi 13 att-site is within the beta-toxin gene. In contrast to the other two phages, phi 13 also introduces the staphylokinase gene (sak) and a second gene related to expression of fib.

Base Composition↗
PubMed1997

Genome structure of the Lactobacillus temperate phage phi g1e: the whole genome sequence and the putative promoter/repressor system.

The complete genome sequence of a Lactobacillus temperate phage phi g1e was established. The double-stranded DNA is composed of 42,259 bp, and encodes for sixty-two possible open reading frames (ORF) as well as several potential regulatory sequences. Based on comparative analysis with other related proteins of the Lactobacillus and Lactococcus phages as well as the Escherichia coli phages (such as lambda), functions were putatively assigned to several phi g1e ORFs: cng and cpg (encoding for repressors), hel (helicase), ntp (NTPase), and several ORFs (e.g., minor capsid proteins). An about 1000-bp DNA region of phi g1e containing cpg and cng was inferred to function as a promoter/repressor system for the phi g1e lysogenic and lytic pathway.

Amino Acid Sequence↗
PubMed1998

Structure of a genome region of the Lactobacillus gasseri temperate phage phiadh covering a repressor gene and cognate promoters.

By sequencing the DNA regions which flank the intG gene encoding integrase of the temperate Lactobacillus (Lb.) gasseri bacteriophage phiadh, a continuous sequence of 6590 bp was established. It encompasses five newly identified ORFs, of which four are located upstream, and one (orfC) downstream of intG. Proteins corresponding to the expected products of the intG upstream coding regions, orfA (33 kDa), orf2 (14 kDa), rad (12.1 kDa), and tec (7.9 kDa), were identified by in vitro expression of subcloned DNA fragments. Rad shares homology with transcription regulators, including SinR of Bacillus species and the repressor of phage phi105. The gporf2 is similar to predicted products of topologically equivalent coding regions of the Lactococcus lactis phage TP901-1 and the B. subtilis phage phi105. Promoters for the divergently oriented rad and tec genes were mapped within the 435-bp region between them and specify overlapping transcripts with extended 5'-untranslated sequences. As shown with lacZ fusions, Rad repressed transcription from the tec and rad promoters 20- and 5-fold, respectively. In Lb. gasseri, weak expression of cloned rad ws sufficient to mediate immunity towards phiadh.

Amino Acid Sequence↗
PubMed1998

Translationally repressive RNA structures monitored in vivo using temperate DNA bacteriophages.

The RNA challenge phage system enables genetic selection of proteins with RNA-binding activity in bacteria. These phages are modified versions of the temperate DNA bacteriophage P22 in which post-transcriptional regulatory events control the developmental fate of the phage. The system was originally developed to identify novel RNA ligands that display reduced affinity for the R17/MS2 coat protein, as well as to select for suppressor coat proteins that recognize mutant RNA ligands. During the course of evaluating whether the HIV-1 Rev protein could direct lysogen development for bacteriophage derivatives that encode Rev response element (RRE) RNA sequences, two examples of RRE RNA ligands that interfere with challenge phage development were identified. In the phage examples described, RRE RNA secondary structure prevents Ant protein biosynthesis and lytic development. Phage lysogen formation occurs efficiently in recipient cells, independent of the expression status of the Rev protein or trans-acting competitor RRE RNA ligands. These studies provide the first example whereby RNA challenge phages may be applied to study RNA folding events and RNA structural interactions in an in vivo context.

Bacterial Proteins↗
PubMed1998

Complete nucleotide sequence and molecular characterization of the temperate staphylococcal bacteriophage phiPVL carrying Panton-Valentine leukocidin genes.

The staphylococcal Panton-Valentine leukocidin (PVL) genes, [lukS-PV-lukF-PV], exist on the genome of a temperate bacteriophage phiPVL isolated from mitomycin C-induced Staphylococcus aureus V8 (ATCC 49775) (Kaneko, J., Kimura, T., Kawakami, Y., Tomita, T., Kamio, Y., 1997b. Panton-Valentine leukocidin genes in phage-like particle isolated from mitomycin C-treated Staphylococcus aureus V8 (ATCC 49775). Biosci. Biotechnol. Biochem. 61, 1960-1962). In this study, the complete nucleotide sequence of the phiPVL genome was analyzed, and the att sites (attL, attR, and attB) required for site-specific integration of phiPVL into the host chromosome were also determined. The linear double-stranded phiPVL genome comprised 41401bp with 3' staggered cohesive ends (cos) of nine bases and contained 63 ORFs, among which the regulatory proteins involved in DNA replication, structural proteins, a holin, a lysin, an integrase, and dUTPase, were tentatively identified by the comparison of the deduced amino acid sequences and by the analysis of the proteins isolated from phiPVL particles. The [lukS-PV-lukF-PV], attP, and int (integrase gene) of phiPVL were all located very close to one another within a 4.0-kb segment on the genome in the order given, and this segment was located at the center from the left and the right cos sites. In addition, the attP region contained five direct repeat sequences that showed a high degree of homology with the recombinase-binding sites of some other S. aureus bacteriophages. The phiPVL genome was found to integrate into an ORF encoding an unknown protein comprising 725 amino acid residues with two leucine zipper-like motifs.

Amino Acid Sequence↗
PubMed1999

Primary structure and features of the genome of the Lactobacillus gasseri temperate bacteriophage (phi)adh.

The complete DNA sequence of the Lactobacillus (Lb.) gasseri temperate phage (phi)adh was determined. The linear and double-stranded genome consists of 43.785bp with a G+C content of 35. 3% and 3' protruding cohesive ends of 12nt. Sixty-two possible ORFs were identified. On the basis of homology comparisons, some of them could be assigned to possible functions, such as a helicase, a nucleic acid polymerase and a protease. In a non-coding area of the (phi)adh genome, structural features of a potential replication origin were detected. After subcloning, this region was functional as a replicon in Lb. gasseri and Lactococcus lactis. N-terminal aa sequencing and electron microscopic analysis of intact and defective phage particles enabled the identification of two capsid protein genes. One of their products, the major head protein, seems to be processed on the posttranslational level.

Amino Acid Sequence↗
PubMed2001

Changes in embryo production results and ovarian recrudescence during the acclimatisation to the semiarid tropics of embryo donor Holstein-Friesian cows raised in a temperate climate.

Pregnant Holstein-Friesian (HF) heifers were transported from central Europe (defined as temperate conditions) to north-eastern Brazil (defined as tropical, semiarid conditions). They were kept in open-sided pens with a hard floor, a roof for shade and sprinkled with water for 10 min every hour if ambient temperature exceeded 30 degrees C. Their diet was balanced to meet nutritional requirements and they were fed twice daily. Control animals were randomly chosen first and second lactation animals located on a farm 25 km away and receiving similar management. Imported animals were superovulated in 1996 (n=63) and 1997 (n=96), compared to 38 and 45 cows in the control herd. The variates recorded were: the interval post-partum to first oestrus; changes in ovarian size and activity; responses to superovulation; and, embryo quality. The average daily milk yields of the imported cows were 20.0 and 23.3 l in 1996 and 1997, respectively compared to 22.1 l throughout the experiment for cows in the control herd. The post-partum anoestrus interval in the imported cows were 112.1+/-30.5 days in 1996 compared to 55.0+/-18.0, 48.2+/-12.0 and 42.6+/-10.7 days in 1997 for control cows. The size and functionality of the ovaries was lowest for the imported animals in 1996 but did not differ between other group-year combinations. These animals also had a lower superovulatory response in 1996 than control cows in terms of the number of ovulations (6.4+/-4.3 versus 13.6+/-5.9, P<0.05) and good quality embryos (1.2+/-0.9 versus 4.4+/-2.1, P<0.05). The two groups of cows did not differ in respect of these characters in the second year of the study. The imported cows had lower reproductive efficiency and responses to superovulation in their first year in their new environment. A period of approximately 1.5 years is required for full adaptation.

Adaptation, Physiological↗
PubMed2000

Comparative study of temperate bacteriophages isolated from Yersinia.

170 Yersinia strains belonging to various species were investigated for the presence of temperate bacteriophages. By induction with mitomycin C seven phages were isolated from Y. enterocolitica strains and one phage from a Y. frederiksenii strain. The phages were characterized on the basis of their morphology, host range, genome size, DNA homology, and protein composition. They belong to different phage families and reveal narrow to moderate wide host ranges. Some of the isolated phages were able to infect pathogenic as well as nonpathogenic strains of Y. enterocolitica. The genomes of all isolated phages were found to be composed of double stranded DNA ranging from about 40 to 60 kb. In addition to the analysed phages, a number of putative phages were induced in strains of Y. frederiksenii, Y. kristensenii, Y. intermedia, and Y. mollaretii. The putative phages were identified by isolation of phage DNA from cell free lysates but could not be propagated on indicator strains. Southern hybridization experiments revealed relationships between phages belonging to different families. Moreover, DNA homologies were observed between phages isolated from nonpathogenic Yersinia strains and a phage which was isolated from a pathogenic Y. enterocolitica serogroup O:3 strain.

Bacteriophage Typing↗
PubMed1999

Induction and characterization of Pediococcus acidilactici temperate bacteriophage

Mitomycin C was used to induce temperate bacteriophage from three strains of Pediococcus acidilactici. The new bacteriophage, designated pa97, pa40, and pa42, were characterized based on morphology, DNA homology, and major protein profiles. Morphological attributes (small isometric heads with non-contractile tails) place these bacteriophages within the B1 group of the family Siphovirdae. Restriction endonuclease digests suggested that the bacteriophage genomes were linear molecules without cohesive ends, and between 33 and 37 kilobases in length. All three bacteriophages possessed one major protein with an estimated mass of 30 to 35 kilodaltons. Bacteriophage pa42 also contained a second major protein of approximately 47 kilodaltons. DNA-DNA hybridization showed bacteriophages pa40 and pa42 were homologous to each other, but not to pa97, suggesting that Pediococcus acidilactici bacteriophage fall into at least two different species.

Journal Article↗
PubMedDate not supplied

Temperate bacteriophages and polyheads produced in the L form of Staphylococcus aureus after mitomycin induction.

A lysogenic strain of Staphylococcus aureus was transformed into its protoplast L form. After stabilization and subcultivation in the L-form state for more than 200 subcultivations, it was tested for maintenance and inducibility of the temperent phage found in the parent strain. In the parent strain and L form, optimal phage production was inducible by 1 and 2 micrograms of mitomycin-C/ml. Besides regular phages with heads of approximately 35 X 85 nm, some L-form cells also produced polyheads of up to more than 1000 nm in length.

L Forms↗
PubMed1992

Evidence and characterization of temperate bacteriophage in Streptococcus salivarius subsp. thermophilus St18.

Lysogenic strains of Streptococcus salivarius subsp. thermophilus were studied using induction with mitomycin C (MC). The induction and presence of temperate phage were investigated carrying out tests on sensitive strains, electron microscopy and phage DNA analysis. Forty-five Str. salivarius subsp. thermophilus strains were subjected to induction with MC and growth of the various cultures was evaluated. Only one strain of those tested showed lysis after adding MC, thus indicating a possible lysogenic state, 0.5 micrograms MC/ml being the optimal dose. Two phi 18 phage-sensitive strains out of 45 were isolated in which this phage behaved as virulent, causing lysis of the culture in broth, but no lysis plaques on agar medium were detected. The St18 strain was cured by u.v. irradiation but no mutants sensitive to the phi 18 phage were found among the clones non-inducible by MC. The presence of phages having a hexagonal isometric head and a long non-contractile tail in the lysate obtained after inducing the St18 strain was confirmed by examination under the electron microscope. Study of the phage DNA showed a genome size of 40.9 +/- 0.5 kb without cohesive end fragments. In addition, the restriction map of the phage genome was constructed. This study has demonstrated lysogeny in Str. salivarius subsp. thermophilus and also that several phage infections of Str. salivarius subsp. thermophilus starters may have an 'endogenous' origin.

Bacteriophages↗
PubMed1999

Desiccation tolerance of Muellerius capillaris first-stage larvae from Israeli arid and French temperate habitats and their compatibility to the land snail Theba pisana.

The survival capacities of Muellerius capillaris (Nematoda: Protostrongylidae) free-living larval stages (L1) of an Israeli desert isolate (Nubian isolate) (92 mm rain per annum) and a French isolate from a temperate habitat (650 mm rain per annum) were compared under humid and extreme dry conditions. Under the dry conditions (7% relative humidity [r.h.] and 33% r.h. at 23 degrees C), both isolates exhibited the same remarkable survival capacity for periods of 17 and 28 days, respectively (> 92% survival, P > 0.1). However, during and after recovery from the anhydrobiotic state, different behaviour patterns of L1 were observed in each isolate. Under humid conditions (97% r.h.) for 10 days, both isolates exhibited similarly low survival percentages (13.4 +/- 4.6%, S.E., survival for the Nubian isolate, 3 +/- 3% for the French isolate, P > 0.05). In water, the French isolate was less active, survived better (52 +/- 8.4% vs 28.7 +/- 3.7, by day 28, P < 0.05) and retained a better morphological appearance (shrunk less) than the Nubian isolate. Larval development of the French isolate in the land snail Theba pisana was significantly faster than that of the Nubian isolate, reaching a higher proportion of infective stages (L3) on day 36 post-infection (78.6% vs 56% P > 0.05). However, similar infection intensities were recovered in snails infected with either of the isolates (59.8 +/- 10.3, S.E., n = 14, for the French isolate, 53 +/- 6, n = 13, for the Nubian isolate, P < 0.05).

Animals↗