New technique in optical resolutions

The present paper illustrates the development of an advanced technique in optical resolution. Both of the amphetamine enantiomers can be obtained by a two-step distillation in nearly quantitative yield without any loss of the resolving agent. It is proved that the second-order interactions (H-bond) are sufficient for separation of enantiomers by distillation. © 1994 Wiley-Liss, Inc.     

Maximization of recombinant protein yield in the insect cell/baculovirus system by one-time addition of nutrients to high-density batch cultures

Suspension cultures of Sf-9 cells at different stages of growth were infected with a recombinant baculovirus expressing -galactosidase, using a range of multiplicities of infection (MOI) of 0.05 to 50. Following infection, the cells were resuspended either in the medium in which they had been grown or in fresh medium. Specific -galactosidase yields were not markedly affected by either MOI or medium change in cultures infected in early exponential phase (3×10⁶ cells mL^–1). In cultures infected at later growth stages, -galactosidase yields could only be maintained by medium replacement. The possibility that this requirement for medium replacement is due either to the accumulation of an inhibitory byproduct or nutrient limitation was examined. Alanine, a major byproduct of cultured insect cell metabolism, did not significantly reduce recombinant protein yield when added to infected cultures in concentrations of up to 40 mM. Following a factorial design, various nutrient concentrates were added alone or in combination to cultures infected in late exponential phase. Additions that included both yeastolate ultrafiltrate and an amino acid mixture restored specific -galactosidase yields to levels observed at earlier growth stages or in late stages with medium replacement; the addition of these concentrates, by permitting production at higher cell density, led to increases in the volumetric yield of recombinant protein. Together or separately, the concentrates when added to uninfected late exponential phase cultures, lead to a doubling of the maximum total cell protein level normally supported by unamended medium.     

Suppressive effect of spinach extract on the formation of melanin in B16 mouse melanoma cells

A non-dialyzable extract of fresh spinach leaves exhibited a strong antioxidant activity towards oxidation of linoleic acid and suppressed the melanin formation of a mouse melanoma cell line, B16 melanoma 4A5, without any significant effect on the proliferation of cells.     

The effect of protein synthesis inhibitors on the glycosylation site occupancy of recombinant human prolactin

The relationship between synthesis and N-liked glycosylation site occupancy of recombinant human prolactin produced from C127 cells was studied with the aid of a battery of protein synthesis inhibitors. Non-lethal concentrations of sodium fluoride, gougerotin, puromycin, anisomycin, and emetine did not alter site occupancy, but low concentrations (<10g ml^–1) of cycloheximide increased the fraction of secreted prolactin bearing oligosaccharide from 20% to 80% of the total. Cycloheximide is an inhibitor of the elongation step of protein synthesis. The observed increase in glycosylation site occupancy upon addition of cycloheximide is consistent with the current opinion that the initial glycosylation event occurs cotranslationally during a limited time period. Cycloheximide may extend this time period by reducing elongation rate. However, the absence of any effect from treatment with other inhibitors of elongation suggests that cycloheximide is unique in its behavior on this system.Abbreviations clp-PRL clipped form of prolactin - DMEM/F12 11 Dulbecco's Modified Eagle's Medium/Ham's nutrient mixture F12 - G-PRL glycosylated (N-linked) fraction of prolaction - NG-PRL prolactin fraction without N-linked glycosylation - PMSF phenylmethylsulfonylfluoride     

Direct determination of the enantiomeric purity of (R)- and (S)-2-hydroxy-4-phenylbutyric acid

The determination of enantiomeric purity of (R)- and (S)-2-hydroxy-4-phenylbutyric acid by chiral HPLC is described. Good resolution has been obtained on covalently bonded L-hydroxyproline saturated with Cu(II) ions. The method makes possible the determination of enantiomeric purity in media containing growing cells. © 1994 Wiley-Liss, Inc.     

Optimization and maintenance of soluble methane monooxygenase activity inMethylosinus trichosporium OB3b

Soluble methane monooxygenase (sMMO) maximization studies were carried out as part of a larger effort directed towards the development and optimization of an aqueous phase, multistage, membrane bioreactor system for treatment of polluted groundwater. A modified version of the naphthalene oxidation assay was utilized to determine the effects of methane:oxygen ratio, nutrient supply, and supplementary carbon sources on maximizing and maintaining sMMO activity inMethylosinus trichosporium OB3b.Methylosinus trichosporium OB3b attained peak sMMO activity (275–300 nmol of naphthol formed h^–1 mg of protein^–1 at 25°C) in early stationary growth phase when grown in nitrate mineral salts (NMS) medium. With the onset of methane limitation however, sMMO activity rapidly declined. It was possible to define a simplified nitrate mineral salts (NMS) medium, containing nitrate, phosphate and a source of iron and magnesium, which allowed reasonably high growth rates (_max 0.08 h^–1) and growth yields (0.4–0.5 g cells/g CH₄) and near maximal activities of sMMO. In long term batch culture incubations sMMO activity reached a stable plateau at approximately 45–50% of the initial peak level and this was maintained over several weeks. The addition of d-biotin, pyridoxine, and vitamin B₁₂ (cyanocobalamin) increased the activity level of sMMO in actively growing methanotrophs by 25–75%. The addition of these growth factors to the simplified NMS medium was found to increase the plateau sMMO level in long term batch cultures up to 70% of the original peak activity.Abbreviations sMMO soluble methane monooxygenase - pMMO particulate methane monooxygenase - NMS nitrate mineral salts - TCE trichloroethene - NADH reduced nicotinamide adenine dinucleotide     

The evolution of pathways for aromatic hydrocarbon oxidation inPseudomonas

The organisation and nucleotide sequences coding for the catabolism of benzene, toluene (and xylenes), naphthalene and biphenylvia catechol and the extradiol (meta) cleavage pathway inPseudomonas are reviewed and the various factors which may have played a part in their evolution are considered. The data suggests that the complete pathways have evolved in a modular way probably from at least three elements. The commonmeta pathway operons, downstream from the ferredoxin-like protein adjacent to the gene for catechol 2,3-dioxygenase, are highly homologous and clearly share a common ancestry. This common module may have become fused to a gene or genes the product(s) of which could convert a stable chemical (benzoate, salicylate, toluene, benzene, phenol) to catechol, thus forming the lower pathway operons found in modern strains. The upper pathway operons might then have been acquired as a third module at a later stage thus increasing the catabolic versatility of the host strains.     

Guanine nucleotide regulatory protein alterations in young Milan hypertensive strain rats

Vascular smooth muscle cell membranes from prehypertensive rats of the Milan hypertensive strain (MHS) were used to examine adenylyl cyclase activity and its regulation by guanine nucleotide regulatory proteins (G-proteins). Basal adenylyl cyclase activity was similar in MHS and Milan normontensive strain (MNS) membranes. Forsokolin (10^?4 M) produced a significantly greater stimulatory response in MHS membranes, but this was not observed with NaF (10^?2 M). Isoporterenol (10^?4 M) caused a significantly decreased stimulation of adenylyl cyclase activity in MHS membranes, while prostaglandin E₁ (10^?5 M) produced similar responses in the two strains. G_i function and GTP responses, as observed by biphasic effects of GTP on isoproterenol-stimulated membranes, were similar in both strains. The levels of G_i2α and G_qα/G₁₁α were similar in the two strains, while the levels of G_sα (44 and 42 kDa forms) and the β-subunit were significantly reduced by ～20% in MHS membranes. The α-subunit of G_i3 was dramatically reduced by ～80% in MHS membranes. The affinities of β-adrenergic receptors for the antagonist, cyanophindolol, were similar in the two strains; however, the number of β-adrenoceptors was substantially reduced in MHS membranes. These findings may be of relevance to altered vascular reactivity and transmembrane ion distribution observed in the MHS.     

Distribution and conservation status of primates in Bioko island,Equatorial Guinea

Ten species of non-human primates are indigenous to Bioko; half of these are endangered and between five and eight are endemic subspecies. Recent data on their status and distribution have been lacking. In 1986, a ten-week survey of the island was carried out to determine the distribution and status of the primates and the natural vegetation, and to evaluate the effects of man on them. This paper presents the results of that survey, gives an update of conservation achievements since 1986, and highlights current concerns. Between 1974 and 1986 it is probable that numbers of all Bioko primates rose as a result of an increase in habitat and of reduced hunting. At the time of the survey there was considerably more natural, undisturbed, vegetation remaining in Bioko tran expected. Much of this vegetation occurs within two large blocks that are of outstanding importance to the conservation of species in tropical Africa, particularly of plants and primates.     

望天树学名研讨

经考证,新组合的望天树学名Ｓｈｏｒｅａ ｃｈｉｎｅｎｓｉｓ Ｈ．Ｚｈｕ ｃｏｍｂ．ｎｏｖ．是不合法的晚出同名,它的合法正确学名应为Ｓｈｏｒｈａ ｗａｎｇｔｉａｎｓｈｕｅａ Ｙ．Ｋ．Ｙａｎｇ ｅｔ Ｊ．Ｋ．Ｗｕ ｎｏｍ．ｎｏｖ．。对其进行订正的明确目的是：根据现行的《国际植物命名法规》的原则,规则,辅则和规程来解决分类及鉴定中可能被混淆的问题。