Humans have co-evolved with a dense community of microbial symbionts that inhabit the lower intestine. In the colon, secreted mucus creates a barrier that separates these microorganisms from the ...intestinal epithelium
. Some gut bacteria are able to utilize mucin glycoproteins, the main mucus component, as a nutrient source. However, it remains unclear which bacterial enzymes initiate degradation of the complex O-glycans found in mucins. In the distal colon, these glycans are heavily sulfated, but specific sulfatases that are active on colonic mucins have not been identified. Here we show that sulfatases are essential to the utilization of distal colonic mucin O-glycans by the human gut symbiont Bacteroides thetaiotaomicron. We characterized the activity of 12 different sulfatases produced by this species, showing that they are collectively active on all known sulfate linkages in O-glycans. Crystal structures of three enzymes provide mechanistic insight into the molecular basis of substrate specificity. Unexpectedly, we found that a single sulfatase is essential for utilization of sulfated O-glycans in vitro and also has a major role in vivo. Our results provide insight into the mechanisms of mucin degradation by a prominent group of gut bacteria, an important process for both normal microbial gut colonization
and diseases such as inflammatory bowel disease
.
Blackleg, caused by Leptosphaeria maculans, is one of the most economically important diseases of Brassica napus worldwide. Two blackleg resistance genes, LepR1 and LepR2, from B. rapa subsp. ...sylvestris (BRS) were previously identified. To transfer LepR1 and LepR2 from BRS into B. napus, interspecific hybridizations were made between the two species to form allotriploids. Analysis of microsatellite markers in two BC1 populations, WT3BC1 and WT4BC1, indicated that segregation fit a 1:1 ratio for BRS and non-BRS alleles on the A-genome linkage groups N2 and N10, the locations of LepR1 and LepR2, respectively. However, recombination frequencies in the allotriploid BC1 populations were at least twice those in the amphidiploid. The number of C-genome chromosomes in the BC1 plants was determined through marker analysis, which indicated averages of 5.9 and 5.0 per plant in the WT3BC1 and WT4BC1 populations, respectively. Two L. maculans isolates, WA51 and pl87-41, were used to differentiate plants carrying resistance genes LepR1 and LepR2. Surprisingly, only 4.0 and 16.6 % of the plants were resistant to isolates WA51 and pl87-41, respectively, in the WT3BC1 population, while 17.9 and 33.3 % of the plants were resistant to these isolates, respectively, in the WT4BC1 population. No association of resistance to isolate WA51 or pl87-41 with linkage group N2 or N10 was found. Based on cotyledon resistance and marker-assisted selection (MAS), BC1 plant WT4-4, which carried a resistance gene similar to LepR1, herein designated LepR1′, and BC2S1 plant WT3-21-25-9, which carried LepR2′, were identified. These plants were successively backcrossed with B. napus and MAS was employed in each generation to reduce non-resistance alleles associated with the BRS genome and to recover the full complement of C-genome chromosomes, resulting in highly blackleg-resistant B. napus lines.
Hibernation is a mammalian strategy that uses metabolic plasticity to reduce energy demands and enable long-term fasting. Fasting mitigates winter food scarcity but eliminates dietary nitrogen, ...jeopardizing body protein balance. Here, we reveal gut microbiome-mediated urea nitrogen recycling in hibernating thirteen-lined ground squirrels (
). Ureolytic gut microbes incorporate urea nitrogen into metabolites that are absorbed by the host, with the nitrogen reincorporated into the squirrel's protein pool. Urea nitrogen recycling is greatest after prolonged fasting in late winter, when urea transporter abundance in gut tissue and urease gene abundance in the microbiome are highest. These results reveal a functional role for the gut microbiome during hibernation and suggest mechanisms by which urea nitrogen recycling may contribute to protein balance in other monogastric animals.
Information on genetic diversity and genetic relationships among genotypes of Brassica carinata is currently limited. The objectives of this study were to evaluate patterns and levels of genetic ...diversity in B. carinata based on amplified fragment length polymorphisms (AFLP) as compared with Brassica juncea and Brassica nigra, and to evaluate agronomic and seed quality data for plants grown in the field in western Canada. A total of 296 AFLP bands were generated from four primer pair combinations and scored for presence/absence in 66, 20 and 7 accessions of B. carinata, B. juncea and B. nigra, respectively. B. carinata was less genetically diverse than the other two species. Differences in diversity were evident in the proportion of polymorphic loci within each species: 23, 35 and 50% for B. carinata, B. nigra and B. juncea, respectively. Pair-wise similarity measures based on the Jaccard coefficient were highest among accessions of B. carinata and showed the narrowest range: 0.911 (0.810-0.981) compared to B. nigra: 0.569 (0.438-0.660) and B. juncea: 0.715 (0.345-0.951). AFLP-based genetic distance information can be used by plant breeders to select diverse genotypes. AFLPs are also useful for fingerprinting cultivars and two primer pair combinations were sufficient to uniquely identify all the accessions of B. carinata. More variation among accessions was identified in the agronomic trial than had previously been described in studies of B. carinata in western Canada, but the data were too limited to draw conclusions regarding specific accessions. Overall, the findings were in agreement with other published work describing the favourable agronomic potential of this species.
Diseases of Camelina sativa (false flax) Séguin-Swartz, G.; Eynck, C.; Gugel, R. K. ...
Canadian journal of plant pathology,
12/2009, Letnik:
31, Številka:
4
Journal Article
Recenzirano
There is renewed interest in the crucifer Camelina sativa (false flax, camelina, gold of pleasure) as an alternative oilseed crop because of its potential value for food, feed, and industrial ...applications. This species is adapted to canola-growing areas in many regions of the world and is generally considered to be resistant to many diseases. A review of the literature indicates that C. sativa is highly resistant to alternaria black spot and blackleg of crucifers. Genotypes resistant to sclerotinia stem rot, brown girdling root rot, and downy mildew can be found among C. sativa accessions, raising the possibility of developing cultivars resistant to these diseases. However, C. sativa is susceptible to clubroot, white rust, and aster yellows disease. Until resistant cultivars or effective management practices have been developed, the susceptibility of C. sativa to these diseases will limit the cultivation of the crop in areas where these diseases are prevalent. Key words: false flax, alternaria black spot, sclerotinia stem rot, root rot, white rust, blackleg, downy mildew, clubroot, aster yellows, Brassicaceae.
La cameline (Camelina sativa) est une espèce oléagineuse de plus en plus recherchée pour l'alimentation humaine et animale et pour des fins industrielles. L'espèce est adaptée aux zones de culture du Colza et de la Navette dans plusieurs régions du monde et est généralement considérée comme étant résistante aux maladies. Une recherche bibliographique a révélé que C. sativa est fortement résistante à l'alternariose et à la nécrose du collet. Certains génotypes de C. sativa sont résistants à la sclérotiniose, au rhizoctone commun ou au mildiou, ce qui permet d'entrevoir le développement de cultivars résistants à ces maladies. Camelina sativa est cependant sensible à la hernie des crucifères, l'albugine et la jaunisse de l'aster. La culture de C. sativa sera limitée dans les régions où ces maladies sont importantes. Mots-clés : cameline, alternariose, sclérotioniose, rhizoctone commun, albugine, nécrose du collet, mildiou, hernie, jaunisse de l'aster, Brassicaceae.
White rust, caused by Albugo candida (Pers.) Kuntze, is an economically important disease of Brassica juncea (L.) Czern and Coss mustard, particularly in India. The most efficient and cost-effective ...way of protecting mustard plants from white rust disease is through genetic resistance. The objective of this study was to identify RAPD markers for white rust resistance in an F1-derived doubled-haploid (DH) population originating from a cross between white rust-susceptible and white rust-resistant breeding lines of B. juncea from the canola-quality B. juncea breeding project of the Agriculture and Agri-Food Canada-Saskatoon Research Centre. The DH population was used to screen for RAPD markers associated with white rust resistance/susceptibility using bulked segregant analysis. Two markers, WR2 and WR3, linked to white rust resistance, flanked the resistance locus Ac2(1) and were highly effective in identifying the presence or absence of the resistance gene in the DH population. These two markers were shown to be specific to the Russian source of white rust resistance utilized in this project. It is concluded that the availability of these RAPD markers will enhance the breeding for white rust resistance in B. juncea.
Clinical trial.
To determine the effect of 2 conservative intervention approaches for functional hallux limitus.
Metatarsophalangeal joint (MPJ) sprains are common and can result in long-term ...sequelae such as persistent pain and loss of range of motion (ROM) secondary to bony proliferation and articular degeneration. It is important to determine the most effective intervention for functional hallux limitus to decrease pain and restore function.
Twenty individuals with first MPJ pain, loss of motion, and weakness participated in the study. All patients received whirlpool, ultrasound, first MPJ mobilizations, calf and hamstring stretching, marble pick-up exercise, cold packs, and electrical stimulation. Ten of the 20 patients (experimental group) also received sesamoid mobilizations, flexor hallucis strengthening exercises, and gait training. Treatment was provided 3 times a week for 4 weeks. Measurements of first MPJ extension ROM, flexor hallucis strength, and subjective pain level were performed on the first and last visits.
Following the 12 therapy sessions, the experimental group achieved significantly greater MPJ extension ROM and flexor hallucis strength and had significantly lower pain levels as compared to the control group (P<.001).
These results suggest that sesamoid mobilization, flexor hallucis strengthening, and gait training should be included in the plan of care when treating an individual with functional hallux limitus.
PDF
