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1.
Seasonal abundance and vertical distribution of mesopelagic calycophoran siphonophores in Monterey Bay, CA 总被引:4,自引:0,他引:4
The seasonal abundance and vertical distribution patterns ofa group of small calycophoran siphonophores (principally Chuniphyesmultidentata and Lensia conoidea) were investigated using aremotely operated vehicle (ROV) deployed in Monterey Bay, California.Abundance was assessed along 295 horizontal transects coveringa depth range of 1001000 m over a three and a half yearperiod. The vertical distribution of the study animals changedseasonally, coupled to the onset and cessation of upwellingin the bay. While numerical abundance peaked after upwelling,there was no significant difference between seasons. The siphonophoreswere more broadly distributed over the depth range sampled duringthe upwelling or Shallow Mixed Layer (SML) period, than duringthe non-upwelling or Deep Mixed Layer (DML) period. There wereno significant differences in abundance or distribution patternsbetween years except in 1993, when there were significantlymore siphonophores observed during the SML period than duringthe DML period. This may reflect effects resulting from the19921993 El Niño event. The abundance of thesesiphonophores was negatively correlated with that of Nanomiabijuga, a physonect siphonophore of similar size and feedingbehavior found in the bay. The siphonophores studied here appearfrom preliminary data to migrate vertically, possibly with twoseparately migrating groups. 相似文献
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R N Patel R S Robison L J Szarka J Kloss J K Thottathil R H Mueller 《Enzyme and microbial technology》1991,13(11):906-912
A key intermediate, (3R-cis)-1,3,4,5-tetrahydro-3-hydroxy-4-(4-methoxyphenyl)-6-(trifluorome thyl)- 2H-1-benzazepin-2-one (compound II or SQ32191), with high optical purity was made by the stereoselective microbial reduction of the parent ketone 1. Several strains of bacterial and yeast cultures were screened for the ability to catalyse the stereoselective reduction of 4,5-dihydro-4-(4-methoxyphenyl)-6-(trifluoromethyl)-1H-1-benzazepin++ +-2,3-dione [compound I or SQ32425]. Microorganisms from the genera Nocardia, Rhodococcus, Alkaligenes, Corynebacterium, Arthrobacter, Hansenula, and Candida reduced compound I to compound II with 60-70% conversion yield. In contrast, microorganisms from the genera Pseudomonas and Acinetobacter reduced compound I stereospecifically to (trans)-1,3,4,5-tetrahydro-3-hydroxy-4-(4-methoxyphenyl)-6-(trifluoromet hyl-2H- 1-benzazepin-2-one (compound III or SQ32408). Among various cultures evaluated, N. salmonicolor SC6310 effectively catalysed the transformation of compound I to compound II with 96% conversion yield at 1.5-2.0 gl-1 concentration. Compound II was isolated and identified by NMR analysis, mass spectrometry, and comparison to an authentic sample. Preparative scale fermentation process and transformation process were developed using cell suspensions of N. salmonicolor SC6310 to catalyse the transformation of compound I to compound II. The isolated compound II had a melting point of 222 degrees C (reference 221-223 degrees C), optical rotation of +130.4 (reference +128 degrees C), and optical purity of greater than 99.9% as analyzed by NMR and chiral HPLC. 相似文献
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Ramesh N. Patel Robert S. Robison Laszlo J. Szarka 《Applied microbiology and biotechnology》1990,34(1):10-14
Summary A key intermediate (S(–) 2-cyclohexyl-1,3-propanediol monoacetate) was made with high optical purity for the total synthesis of a new angiotensin converting enzyme inhibitor, Fosinopril. The stereoselective hydrolysis of 2-cyclohexyl-1,3-propanediol diacetate (I) and 2-phenyl-1,3-propanediol diacetate (II) was carried out with lipases. Among various lipases evaluated, only porcine pancreatic lipase (PPL) and Chromobacterium viscosum lipase demonstrated efficient conversion and gave the desired enantiomer of monoacetate. In aqueous solution, the desired S(–) monoacetate exhibited an optical purity of 65%–80% (30%–60% enantiomeric excess [e.e.]). However, when the same reactions were conducted in a biphasic system, the product S(–) monoacetate exhibited an optical purity of 99%–100% (98%–100% e.e.). The high purity product was achieved with 65 mol% yield at 1% substrate concentration. Among various solvents evaluated in biphasic systems, efficient hydrolysis was achieved in toluene, cyclohexane, and trichloro-trifluoroethane. The crude PPL was partially purified and two lipase fractions (A and B) were identified. Lipases A and B had a molecular mass of 38 000 and 40 000 daltons, respectively, and both were found to catalyze the hydrolysis of I and II to the appropriate monoacetate in a biphasic system.
Offprint requests to: R. N. Patel 相似文献
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Direct sequencing of the mitochondrial displacement loop (D-loop) of shrews
(genus Sorex) for the region between the tRNA(Pro) and the conserved
sequence block-F revealed variable numbers of 79-bp tandem repeats. These
repeats were found in all 19 individuals sequenced, representing three
subspecies and one closely related species of the masked shrew group (Sorex
cinereus cinereus, S. c. miscix, S. c. acadicus, and S. haydeni) and an
outgroup, the pygmy shrew (S. hoyi). Each specimen also possessed an
adjacent 76-bp imperfect copy of the tandem repeats. One individual was
heteroplasmic for length variants consisting of five and seven copies of
the 79-bp tandem repeat. The sequence of the repeats is conducive to the
formation of secondary structure. A termination-associated sequence is
present in each of the repeats and in a unique sequence region 5' to the
tandem array as well. Mean genetic distance between the masked shrew taxa
and the pygmy shrew was calculated separately for the unique sequence
region, one of the tandem repeats, the imperfect repeat, and these three
regions combined. The unique sequence region evolved more rapidly than the
tandem repeats or the imperfect repeat. The small genetic distance between
pairs of tandem repeats within an individual is consistent with a model of
concerted evolution. Repeats are apparently duplicated and lost at a high
rate, which tends to homogenize the tandem array. The rate of D- loop
sequence divergence between the masked and pygmy shrews is estimated to be
15%-20%/Myr, the highest rate observed in D-loops of mammals. Rapid
sequence evolution in shrews may be due either to their high metabolic rate
and short generation time or to the presence of variable numbers of tandem
repeats.
相似文献
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大鼠胼胝体内神经肽Y免疫反应阳性纤维的发育 总被引:1,自引:0,他引:1
本实验用免疫组织化学ABC法研究了大鼠胼胝体内神经肽Y免疫反应阳性(NPY-IR)纤维的生后发育。结果发现,许多NPY-IR纤维在大鼠出生时便存在于胼胝体内。NPY-IR胼胝体纤维的密度在生后1周内继续逐渐增高,在第2周内达到最高峰。之后,NPY-IR胼胝体纤维的密度逐渐下降,至第3周末时接近成年时的水平,即仅有少量NPY-IR纤维存在于胼胝体内。这些结果提示在大鼠早期生后发育过程中许多NPY-IR胼胝体纤维是暂时性的,其作用可能与大脑皮质的机能发育有关。 相似文献