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81.
82.
Gopaul Kotturi Campbell W. Robinson William E. Inniss 《Applied microbiology and biotechnology》1991,34(4):539-543
Summary Cell growth and phenol degradation kinetics were studied at 10°C for a psychrotrophic bacterium, Pseudomonas putida Q5. The batch studies were conducted for initial phenol concentrations, So, ranging from 14 to 1000 mg/1. The experimental data for 14<=So<=200 mg/1 were fitted by non-linear regression to the integrated Haldane substrate inhibition growth rate model. The values of the kinetic parameters were found to be: m=0.119 h–1, K
S=5.27 mg/1 and K
I=377 mg/1. The yield factor of dry biomass from substrate consumed was Y=0.55. Compared to mesophilic pseudomonads previously studied, the psychrotrophic strain grows on and degrades phenol at rates that are ca. 65–80% lower. However, use of the psychrotrophic microorganism may still be economically advantageous for waste-water treatment processes installed in cold climatic regions, and in cases where influent waste-water temperatures exhibit seasonal variation in the range 10–30°C.Nomenclature
K
S
saturation constant (mg/l)
-
K
I
substrate inhibition constant (mg/l)
-
specific growth rate (h–1)
- m
maximum specific growth rate without substrate inhibition (h–1)
- max
maximum achievable specific growth rate with substrate inhibition (h–1)
- S
substrate (phenol) concentration (mg/l)
- So
initial substrate concentration (mg/l)
- Smax
substrate concentration corresponding to max (mg/l)
-
t
time (h)
- X
cell concentration, dry basis (mg DW/l)
- Xf
final cell concentration, dry basis (mg DW/l)
- Xo
initial cell concentration, dry basis (mg DW/l)
- Y
yield factor (mg DW cell produced/mg substrate consumed) 相似文献
83.
S W Scherer G Otulakowski B H Robinson L C Tsui 《Cytogenetics and cell genetics》1991,56(3-4):176-177
84.
Molecular detection of microscopic and submicroscopic deletions associated with Miller-Dieker syndrome. 总被引:22,自引:12,他引:10
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P vanTuinen W B Dobyns D C Rich K M Summers T J Robinson Y Nakamura D H Ledbetter 《American journal of human genetics》1988,43(5):587-596
Miller-Dieker syndrome (MDS), a disorder manifesting the severe brain malformation lissencephaly ("smooth brain"), is caused, in the majority of cases, by a chromosomal microdeletion of the distal short arm of chromosome 17. Using human chromosome 17-specific DNA probes, we have begun a molecular dissection of the critical region for MDS. To localize cloned DNA sequences to the MDS critical region, a human-rodent somatic cell hybrid panel was constructed which includes hybrids containing the abnormal chromosome 17 from three MDS patients with deletions of various sizes. Three genes (myosin heavy chain 2, tumor antigen p53, and RNA polymerase II) previously mapped to 17p were excluded from the MDS deletion region and therefore are unlikely to play a role in its pathogenesis. In contrast, three highly polymorphic anonymous probes, YNZ22.1 (D17S5), YNH37.3 (D17S28), and 144-D6 (D17S34), were deleted in each of four patients with visible deletions, including one with a ring chromosome 17 that is deleted for a portion of the single telomeric prometaphase subband p13.3. In two MDS patients with normal chromosomes, a combination of somatic cell hybrid, RFLP, and densitometric studies demonstrated deletion for YNZ22.1 and YNH37.3 in the paternally derived 17's of both patients, one of whom is also deleted for 144-D6. The results indicate that MDS can be caused by submicroscopic deletion and raises the possibility that all MDS patients will prove to have deletions at a molecular level. The two probes lie within a critical region of less than 3,000 kb and constitute potential starting points in the isolation of genes implicated in the severe brain maldevelopment in MDS. 相似文献
85.
Inheritance of colour and coat in the Belgian Shepherd dog 总被引:1,自引:0,他引:1
R. Robinson 《Genetica》1988,76(2):139-141
The several colours and coats of the Belgian Shepherd dog are shown to be due primary to combinations of the following genes: dominant black (A
s
), dominant yellow (A
y
), chinchilla (ch), long hair (l) and wire hair (Wh). The gene for black and tan (a
t
) is or has been present in the breed. All of the dominant yellow dogs exhibit a black facial mask and extensive suffusion of black guard hairs on the body. 相似文献
86.
Experimental effects of elevated salinity on three benthic invertebrates in Pyramid Lake,Nevada 总被引:7,自引:7,他引:0
Salinity of Pyramid Lake increased from 3.7 to 5.5 between 1933 and 1980. Concern over future reductions in overall species richness prompted experiments to assess responses of dominant lake organisms to elevated salinity. Salinity tolerances of three important benthic invertebrates, Hyalella aztecta, Chironomus utahensis, and Heterocypris sp., were tested in controlled laboratory bioassays and also in a semi-natural environment consisting of large (47 m3) mesocosms.Densities of H. azteca in mesocosms were significantly lower at salinities of 8.0 and 11.0 compared with 5.6 controls in year one, but not in 8.5 salinity mesocosms in year two. The 96-h LC50 for H. azteca was high at 19.5. Short-term mortalities of C. utahensis were 100% at salinities of 13.3 and greater. Fifty-seven percent fewer larvae matured from third to fourth instar at 8.9 than at 5.5 salinity in 17 day subacute bioassays. Furthermore, larval chironomid densities and emergence of adults from mesocosms were significantly reduced at salinities of 8.0 and higher compared with controls. Mortality of Heterocypris sp. was 50% at a salinity of 18.6 in laboratory bioassays and populations in mesocosms ranged between 40 and 100% lower at salinities of 8.0 and 11.0 than in controls.Multiple generation mesocosm experiments indicated all three invertebrates were more sensitive to elevated salinity than results of short-term bioassays. Our studies suggest populations of these invertebrates may be reduced from present levels if Pyramid Lake's salinity were to double, although none are expected to be extirpated. Food habit shifts and reduced production of lake fishes are likely consequences of salinity-induced disruption in the benthic invertebrate forage base. 相似文献
87.
The phytoplankton and nutrient status of the embayments between Penetanguishene and Waubaushene in southern Georgian Bay (Severn Sound) were examined during the ice-free periods of 1973–1982 because the area showed symptoms of excessive nutrient enrichment. Four wastewater treatment plants currently discharge to the area, another is under construction and a sixth plant has been proposed. Except for Penetang Bay, the area is well-mixed by prevailing winds but is somewhat isolated from the main part of Georgian Bay. Average phytoplankton biomasses throughout the area were 10–20× higher than values from adjacent Nottawasaga Bay where, during 1980, total phytoplankton biomass ranged between 0.15 and 0.25 mm3 · l–1. Total phosphorus concentrations were highest in Penetang Bay, ranging between 30 and 49 µg P · l–1 (May–September means) over the 10 year period. Phosphorus concentrations in Nottawasaga Bay averaged 4–6 µg P · l–1 and no significant differences were detected among the sampling stations; however, phytoplankton densities at stations near urban centres and river inflows were significantly higher than at more remote offshore sites and attests to the use of phytoplankton as a sensitive measure of trophic status in Georgian Bay.Although improvement of Severn Sound water quality to a level comparable to that presently existing in Nottawasaga Bay may never be practical, steps are being taken to control high industrial phosphorus loading and to lessen bypassing of sewage treatment facilities previously hydraulically overloaded during periods of heavy runoff. These measures, along with an evaluation of other major sources of nutrients to Severn Sound, should enable a refinement of the nutrient management programme for Severn Sound and some improvement in trophic status. 相似文献
88.
Homologous recombination between human immunodeficiency viral DNAs in cultured human cells: analysis of the factors influencing recombination 总被引:1,自引:0,他引:1
S Kalyanaraman R Jannoun-Nasr D York P A Luciw R Robinson A Srinivasan 《Biochemical and biophysical research communications》1988,157(3):1051-1060
Recombination between HIV DNAs was analyzed using DNA transfection in cell cultures and the optimal conditions for efficient recombination were determined. Recombinant plasmid DNA substrates were constructed from HIV proviral DNAs and the success of recombination was measured by the production of viable hybrid virus. The process of recombination between HIV DNAs was shown to be i) dependent on homology between the truncated HIV DNAs and ii) maximum with concentrations of the truncated DNAs 3ug and above. HIV isolates with heterogeneity in their primary sequence, thus offer an ideal system for the analysis of the requirement of homologous recombination. In addition, recombination methodology would be useful for generating hybrid HIVs for the analysis of specific viral gene functions. 相似文献
89.
Tryptophan (Trp) fluorescence quenching of phytochrome has been studied using anionic, cationic and neutral quenchers, I-, Cs+ and acrylamide, respectively, in an effort to understand the molecular differences between the Pr and Pfr forms. The data have been analyzed using both Stern-Volmer and modified Stern-Volmer kinetic treatments. The anionic quencher, I-, was proven to be an ineffective quencher with Stern-Volmer constants, Ksv, of 0.60 and 0.63 M-1, respectively, for the Pr and Pfr forms of phytochrome. The cationic quencher, Cs+, showed about a 2-fold difference in the Ksv of Pr and Pfr, indicating a significant change in the fluorescent Trp environments during the Pr to Pfr phototransformation. However, only 25-37% of the fluorescent Trp residues were accessible to the cationic quencher. Most of the fluorescent Trp residues were accessible to acrylamide, but the quenching by acrylamide was indistinguishable for the Pr and Pfr forms. An additional quenching by acrylamide after a saturated quenching with Cs+ showed more than 40% increase in the Ksv of Pfr over Pr. These observations, along with the finding of two distinct components in the Trp fluorescence lifetime, indicate the existence of Trp residues in at least two different sets of environments in the phytochrome protein. The two components of the fluorescence had lifetimes of 1.1 ns (major) and 4.7 ns (minor) for Pr and 0.9 ns (major) and 4.6 ns (minor) for Pfr. Fluorescence quenching was found to be both static and dynamic as the Stern-Volmer constants for the steady-state fluorescence quenching were higher than for the dynamic fluorescence quenching. Based on the quenching results, in combination with the location of Trp residues in the primary structure, we conclude that the Pr to Pfr phototransformation involves a significant conformation change in the phytochrome molecule, preferentially in the 74 kDa chromophore-bearing domain. 相似文献
90.
Nucleolar organiser regions (NORs) were examined in over 90% of the species of Australian ground frogs (familiy Myobatrachidae),
including representatives from all twenty currently recognised genera and the three subfamilies. Throughout the family, location
of the NOR within the karyotype showed considerable variation yet karyotype morphology showed uniformity. The precise mechanism(s)
whereby variation in NOR location evolved while karyotype morphology was unchanged remains uncertain. Comparison of the two
major subfamilies showed that the Limnodynastinae had a greater diversity of NOR location than the Myobatrachinae. The limnodynastine
genus,Heleioporus, was the only one to show multiple NOR sites in several species. NOR location was particularly stable within most polytypic
genera. Differences in NOR location within the remaining polytypic genera (Heleioporus, Limnodynastes, Neobatrachus, Philoria andRanidella) pointed to taxonomic discriminations that were generally consistent with recent proposals based on other criteria. 相似文献