The prominent feature of rhizobia is their molecular dialogue with plant hosts. Such interaction is enabled by the presence of a series of symbiotic genes encoding for the synthesis and export of ...signals triggering organogenetic and physiological responses in the plant. The genome of the
Rhizobium sullae
type strain IS123
T
nodulating the legume
Hedysarum coronarium
, was sequenced and resulted in 317 scaffolds for a total assembled size of 7,889,576 bp. Its features were compared with those of genomes from rhizobia representing an increasing gradient of taxonomical distance, from a conspecific isolate (
Rhizobium sullae
WSM1592), to two congeneric cases (
Rhizobium leguminosarum
bv.
viciae
and
Rhizobium etli
) and up to different genera within the legume-nodulating taxa. The host plant is of agricultural importance, but, unlike the majority of other domesticated plant species, it is able to survive quite well in the wild. Data showed that that the type strain of
R. sullae
, isolated from a wild host specimen, is endowed with a richer array of symbiotic genes in comparison to other strains, species or genera of rhizobia that were rescued from domesticated plant ecotypes. The analysis revealed that the bacterium by itself is incapable of surviving in the extreme conditions that its host plant can tolerate. When exposed to drought or alkaline condition, the bacterium depends on its host to survive. Data are consistent with the view of the plant phenotype as the primary factor enabling symbiotic nitrogen fixing bacteria to survive in otherwise limiting environments.
Summary
Recent advances in genomics and molecular biology are providing an excellent opportunity to get a glimpse into the past, to examine the present, and to predict the future evolution of ...pathogenic mycobacteria, and in particular that of Mycobacterium tuberculosis, the agent of human tuberculosis. The recent availability of genome sequences of several Mycobacterium canettii strains, representing evolutionary early‐branching tubercle bacilli, has allowed the genomic and molecular features of the putative ancestor of the M. tuberculosis complex (MTBC) to be reconstituted. Analyses have identified extensive lateral gene transfer and recombination events in M. canettii and/or the MTBC, leading to suggestions of a past environmental reservoir where the ancestor(s) of the tubercle bacilli might have adapted to an intracellular lifestyle. The daily increases in M. tuberculosis genome data and the remaining urgent Public Health problem of tuberculosis make it more important than ever to try and understand the origins and the future evolution of the MTBC. Here we critically discuss a series of questions on gene‐loss, acquisition, recombination, mutation and conservation that have recently arisen and which are key to better understand the outstanding evolutionary success of one of the most widespread and most deadly bacterial pathogens in the history of humankind.
The prominent feature of rhizobia is their molecular dialogue with plant hosts. Such interaction is enabled by the presence of a series of symbiotic genes encoding for the synthesis and export of ...signals triggering organogenetic and physiological responses in the plant. The genome of the
type strain IS123
nodulating the legume
, was sequenced and resulted in 317 scaffolds for a total assembled size of 7,889,576 bp. Its features were compared with those of genomes from rhizobia representing an increasing gradient of taxonomical distance, from a conspecific isolate (
WSM1592), to two congeneric cases (
bv.
and
) and up to different genera within the legume-nodulating taxa. The host plant is of agricultural importance, but, unlike the majority of other domesticated plant species, it is able to survive quite well in the wild. Data showed that that the type strain of
, isolated from a wild host specimen, is endowed with a richer array of symbiotic genes in comparison to other strains, species or genera of rhizobia that were rescued from domesticated plant ecotypes. The analysis revealed that the bacterium by itself is incapable of surviving in the extreme conditions that its host plant can tolerate. When exposed to drought or alkaline condition, the bacterium depends on its host to survive. Data are consistent with the view of the plant phenotype as the primary factor enabling symbiotic nitrogen fixing bacteria to survive in otherwise limiting environments.
In a prospective, randomized, double-blind study the effects on infection rates of a 1-day and a 3-day course of cefuroxime versus placebo were studied in patients undergoing peripheral vascular ...surgery. During a 30-month study period 211 patients were randomized to one of three treatment groups: Group I Placebo; Group II cefuroxime 1 day; Group III cefuroxime 3 days. Cefuroxime was administered intravenously (1.5 g every 8 hours) and the first dose was given 1 hour before surgery. Wound infection rates in the three treatment groups were: Group I 16.7%; Group II 3.8% (p less than 0.05 vs placebo); Group III 4.3% (p less than 0.05 vs placebo). One graft infection occurred in 110 patients at risk (0.9%) and this occurred in the placebo group. No allergic reactions or other side effects were noted in any of the treatment groups. No cefuroxime-resistant bacteria were found in Group II or III. In conclusion, prophylactic administration of cefuroxime during 1 day significantly reduced the incidence of infectious complications following peripheral vascular surgery. Extension of the prophylaxis beyond the day of surgery offered no additional effect. The study supports the use of short-term prophylactic antibiotics in vascular surgery.
Relations between the energy transferred by a high-velocity missile along a wound channel and the ensuing tissue destruction were studied in 25 live, anesthetized pigs. They were wounded in the ...muscular parts of the hind legs by an assault rifle bullet or by a spherical steel ball at about 1,000 m/s. The penetration of the assault rifle bullets was recorded by a stereo, multichannel flash X-ray arrangement. The energy transfer in the wound was evaluated from the X-rays. The wounds were surgically debrided in sections by a skilled surgeon. The energy transfer of the spherical steel bullets was measured. These animals had the thigh surrounded with a plaster of Paris cast, in order to suppress, as far as possible, the formation of the temporary cavity. The wounds were debrided. The amounts of tissue debrided were weighed and utilized as a measure of the extent of the injury. Good and consistent correlations between energy transfer and tissue debridement were obtained for the wound types studied. The amount of tissue debrided diminished by about 40% for the plaster-covered animals. Influence of boundary effects could be studied, and the results give indications of the mechanisms of missile wounding.
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