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1.
Thirty-nine samples of freshly drawn ewes' milk collected at 13 farms, and 120 samples of raw ewes' milk collected on arrival at a dairy were examined. Farm samples had geometric mean counts of 4.4 X 10(2) Enterobacteriaceae/ml, 3.9 X 10(2) coliforms/ml and 2.0 X 10(2) faecal coliforms/ml, whereas the respective mean counts were 6.2 X 10(3)/ml, 5.4 X 10(3)/ml and 1.3 X 10(3)/ml for dairy samples. Salmonellas were not detected by enrichment procedures in any of the 159 samples examined. Escherichia coli (47.5% strains), Enterobacter cloacae (17.7%), Ent. agglomerans (11.3%), Hafnia alvei (6.5%) and Klebsiella oxytoca (6.0%) were the predominant species in 434 Enterobacteriaceae strains isolated from farm samples. Levels and species of Enterobacteriaceae found in the present work in raw ewes' milk imply a considerable risk of early blowing in cheese-making from unpasteurized milk. 相似文献
2.
Of 124 staphylococcal strains isolated from sheep milk, 78 produced enterotoxin A, B, C, or D when evaluated by an enzyme-linked immunosorbent assay. Enterotoxins A and D, elaborated by 44 and 43 strains, respectively, showed the highest incidence. Enterotoxin production by coagulase-negative strains (one Staphylococcus cohnii, three S. epidermidis, five S. haemolyticus, and four S. xylosus) was detected. Linear and logarithmic-logarithmic regressions of optical density on enterotoxin concentration yielded the best-fitting equations for enterotoxin quantitation. A significantly higher incidence of enterotoxin producers and significantly higher levels of enterotoxins produced were recorded for coagulase-positive, thermostable nuclease-positive, hemolysis-positive, or mannitol-positive strains. Mannitol utilization was the best test for discriminating between enterotoxigenic and nonenterotoxigenic staphylococci. 相似文献
3.
A comparative description of mitochondrial DNA differentiation in selected avian and other vertebrate genera 总被引:14,自引:1,他引:13
Levels of mitochondrial DNA (mtDNA) sequence divergence between species
within each of several avian (Anas, Aythya, Dendroica, Melospiza, and
Zonotrichia) and nonavian (Lepomis and Hyla) vertebrate genera were
compared. An analysis of digestion profiles generated by 13-18 restriction
endonucleases indicates little overlap in magnitude of mtDNA divergence for
the avian versus nonavian taxa examined. In 55 interspecific comparisons
among the avian congeners, the fraction of identical fragment lengths (F)
ranged from 0.26 to 0.96 (F = 0.46), and, given certain assumptions, these
translate into estimates of nucleotide sequence divergence (p) ranging from
0.007 to 0.088; in 46 comparisons among the fish and amphibian congeners, F
values ranged from 0.00 to 0.36 (F = 0.09), yielding estimates of P greater
than 0.070. The small mtDNA distances among avian congeners are associated
with protein-electrophoretic distances (D values) less than approximately
0.2, while the mtDNA distances among assayed fish and amphibian congeners
are associated with D values usually greater than 0.4. Since the
conservative pattern of protein differentiation previously reported for
many avian versus nonavian taxa now appears to be paralleled by a
conservative pattern of mtDNA divergence, it seems increasingly likely that
many avian species have shared more recent common ancestors than have their
nonavian taxonomic counterparts. However, estimates of avian divergence
times derived from mtDNA- and protein-calibrated clocks cannot readily be
reconciled with some published dates based on limited fossil remains. If
the earlier paleontological interpretations are valid, then protein and
mtDNA evolution must be somewhat decelerated in birds. The empirical and
conceptual issues raised by these findings are highly analogous to those in
the long-standing debate about rates of molecular evolution and times of
separation of ancestral hominids from African apes.
相似文献
4.
Ann Buchanan Josué Díaz-Delgado Gaya Balamayooran Maritza Anguiano Kátia Groch Lana Krol 《Journal of medical primatology》2020,49(6):341-343
Hematopoietic neoplasia other than lymphoma and leukemia is uncommon among non-human primates. Herein, we provide the first evidence of occurrence of leukemic histiocytic sarcoma in a captive common squirrel monkey with Saimiriine Gammaherpesvirus 2 (Rhadinovirus), Saimiri sciureus lymphocryptovirus 2 (Lymphocryptovirus), and Squirrel monkey retrovirus (β-Retrovirus) coinfection. 相似文献
5.
Ignacio Pérez-Valero Alicia González-Baeza Miriam Estébanez María L. Montes-Ramírez Carmen Bayón Federico Pulido José I. Bernardino Francisco X. Zamora Susana Monge Francisco Gaya María Lagarde Rafael Rubio Asunción Hernando Francisco Arnalich José R. Arribas 《PloS one》2013,8(7)
Background
In patients who remain virologically suppressed in plasma with triple-drug ART a switch to protease inhibitor monotherapy maintains high rates of suppression; however it is unknown if protease inhibitor monotherapy is associated to a higher rate of neurocognitive impairment.Methods
In this observational, cross-sectional study we included patients with plasma virological suppression (≥1 year) without concomitant major neurocognitive confounders, currently receiving for ≥1 year boosted lopinavir or darunavir as monotherapy or as triple ART. Neurocognitive impairment was defined as per the 2007 consensus of the American Association of Neurology. The association between neurocognitive impairment and protease inhibitor monotherapy, adjusted by significant confounders, was analysed.Results
Of the 191 included patients - triple therapy: 96, 1–2 years of monotherapy: 40 and >2 years of monotherapy: 55 - proportions (95% CI) with neurocognitive impairment were: overall, 27.2% (20.9–33.6); triple therapy, 31.6% (22.1–41.0); short-term monotherapy, 25.0% (11.3–38.7); long-term monotherapy: 21.4% (10.5–32.3); p = 0.38. In all groups, neurocognitive impairment was mildly symptomatic or asymptomatic by self-report. There were not significant differences in Global Deficit Score by group. In the regression model confounding variables for neurocognitive impairment were years on ART, ethnicity, years of education, transmission category and the HOMA index. Adjusted by these variables the Odds Ratio (95% CI) for neurocognitive impairment of patients receiving short-term monotherapy was 0.85 (0.29–2.50) and for long-term monotherapy 0.40 (0.14–1.15).Conclusions
Compared to triple drug antiretroviral therapy, monotherapy with lopinavir/ritonavir or darunavir/ritonavir in patients with adequate plasma suppression was not associated with a higher rate of asymptomatic neurocognitive impairment than triple drug ART. 相似文献6.
7.
HIV-1 Nef modulates disease progression through interactions with over 30 host proteins. Individual chains fold into membrane-interacting N-terminal and C-terminal core (Nefcore) domains respectively. Nef exists as small oligomers near membranes and associates into higher oligomers such as tetramers or hexadecamers in the cytoplasm. Earlier structures of the Nefcore in apo and complexed forms with the Fyn-kinase SH3 domain revealed dimeric association details and the role of the conserved PXXP recognition motif (residues 72–78) of Nef in SH3-domain interactions. The crystal structure of the tetrameric Nef reported here corresponds to the elusive cytoplasmic stage. Comparative analyses show that subunits of Nefcore dimers (open conformation) swing out with a relative displacement of ∼22 Å and rotation of ∼174° to form the ‘closed’ tetrameric structure. The changes to the association are around Asp125, a conserved residue important for viral replication and the important XR motif (residues 107–108). The tetramer associates through C4 symmetry instead of the 222 symmetry expected when two dimers associate together. This novel dimer-tetramer transition agrees with earlier solution studies including small angle X-ray scattering, analytical ultracentrifugation, dynamic laser light scattering and our glutaraldehyde cross-linking experiments. Comparisons with the Nefcore—Fyn-SH3 domain complexes reveal that the PXXP motif that interacts with the SH3-domain in the dimeric form is sterically occluded in the tetramer. However the 151–180 loop that is distal to the PXXP motif and contains several protein interaction motifs remains accessible. The results suggest how changes to the oligomeric state of Nef can help it distinguish between protein partners. 相似文献
8.
9.
P Minakshi R Singh K Ranjan P Kumar CG Joshi YK Reddy G Prasad 《Journal of virology》2012,86(15):8337-8338
In this article, we document the first complete genome sequence of an isolate of bluetongue virus serotype 16 (BTV16) from a goat in India. The virus was isolated from an in-contact goat from an animal farm in Chennai where clinical disease occurs in sheep. The total size of the genome is 19,185 bp. The information provided for full-length sequences of all 10 segments will help in understanding the geographical origin and transmission of the Indian isolate of BTV16 as well as its comparison with global isolates of BTV16 of sheep, cattle, and other host species origins. 相似文献
10.
RIG-I like receptors (RLR) that recognize non-self RNA play critical roles in activating host innate immune pathways in response to viral infections. Not surprisingly, RLRs and their associated signaling networks are also targeted by numerous antagonists that facilitate viral pathogenesis. Although the role of RLRs in orchestrating antiviral signaling has been recognized for some time, our knowledge of the complex regulatory mechanisms that control signaling through these key molecules is incomplete. A series of recent structural studies shed new light into the structural basis for dsRNA recognition and activation of RLRs. Collectively, these studies suggest that the repression of RLRs is facilitated by a cis element that makes multiple contacts with domains within the helicase and that RNA binding initiated by the C-terminal RNA binding domain is important for ATP hydrolysis and release of the CARD domain containing signaling module from the repressed conformation. These studies also highlight potential differences between RIG-I and MDA5, two RLR members. Together with previous studies, these new results bring us a step closer to uncovering the complex regulatory process of a key protein that protects host cells from invading pathogens. 相似文献