Isolation, characterization and chromosomal mapping of the mouse tyrosine aminotransferase gene

The tyrosine aminotransferase (TAT) gene is expressed in a tissue and developmental-specific manner. In addition, this gene is regulated by glucocorticoid and polypeptide hormones and its expression is affected when a regulatory region near the albino locus of the mouse is deleted. In order to allow studies of the molecular effects of these deletion mutations we have isolated and characterized the mouse TAT gene. The gene is 9.2 x 10(3) bases in length and consists of 12 exons which give rise to a 2.3 x 10(3) base long messenger RNA. The DNA sequence at the 5' end of the gene was determined and compared with the corresponding sequence of the rat tyrosine aminotransferase gene. The sequence comparison showed extensive homology over the entire region sequenced. In addition, DNA: DNA heteroduplex studies between the mouse and rat tyrosine aminotransferase genes revealed that this homology extends over the entire gene and its flanking sequences. The mouse tyrosine aminotransferase gene has been mapped distal to the serum esterase-1 locus on mouse chromosome 8, using a restriction fragment length polymorphism between two mouse species. Since the albino deletions are located on mouse chromosome 7, the assignment of the TAT gene to chromosome 8 suggests that a regulatory factor(s) affecting TAT gene expression acts in trans.     

ATP synthesis in Methanobacterium thermoautotrophicum coupled to CH4 formation from H2 and CO2 in the apparent absence of an electrochemical proton potential across the cytoplasmic membrane

Methanogenic bacteria are considered to couple methane formation with the synthesis of ATP by a chemiosmotic mechanism. This hypothesis was tested with Methanobacterium thermoautotrophicum. Methane formation from H2 and CO2 (2.5 - 3 mumol X min-1 X mg cells-1) by cell suspensions of this organism resulted in the formation of an electrochemical proton potential (delta mu H +) across the cytoplasmic membrane of 230 mV (inside negative) and in the synthesis of ATP up to an intracellular concentration of 5 - 7 nmol/mg. The addition of ionophores at concentrations which completely dissipated delta mu H + without inhibiting methane formation did not result in an inhibition of ATP synthesis. It thus appears that delta mu H + across the cytoplasmic membrane is not the driving force for the synthesis of ATP in M. thermoautotrophicum.     

Pharmacokinetics of 19-nortestosterone esters in normal men

A reliable method for the isolation of 19-nortestosterone (NT), testosterone (T) and dihydrotestosterone (DHT) by high-performance liquid chromatography (HPLC) and quantitation of the individual steroids by radioimmunoassays is described. The method was used to measure serum concentrations of NT, T and DHT in a pharmacokinetic study and in a clinical trial for male fertility control. Following intramuscular injection of either 50 mg 19-nortestosterone-3-(p-hexoxyphenyl)-propionate (NP) or 50 mg 19-nortestosterone-decanoate (ND) serum NT increased rapidly to maximal concentrations of 4.6 +/- 3.2 and 2.0 +/- 1.3 nmol/l (+/-SD), respectively, in the 6 volunteers. The half-life time was 8 days for ND and 21 days for NP. Based on these findings a clinical trial with NP was performed. NP was given to 5 healthy men in doses of 100 mg/week for the first 3 weeks followed by 200 mg/week for 10 further weeks. Serum NT levels increased gradually and maximal concentrations were reached in the 13th treatment week (20.2 +/- 3.4 nmol/l). Measurable amounts of NT were detectable for 19 weeks after the last injection. The study shows that NT accumulates under this treatment regime and wider spacing of the injection intervals may be possible in future trials.     

d-2-hydroxyisocaproate dehydrogenase from Lactobacillus casei

Summary The new enzyme d-2-hydroxyisocaproate dehydrogenase (NAD⁺-dependent) was detected in strains of the genus Lactobacillus and related genera. Straight and branched chain aliphatic as well as aromatic 2-ketocarboxylic acids are stereospecifically reduced to the corresponding d-2-hydroxycarboxylic acids according to the following equation:R-CO-COOH + NADH + H⁺ R-CHOH-COOH + NAD⁺ The enzyme is called d-hydroxyisocaproate dehydrogenase by us because 2-ketoisocaproate is the substrate with the lowest K_M-value. NAD(H) as a cofactor cannot be replaced by NADP(H). Because of its broad substrate specificity we chose the strain Lactobacillus casei ssp. pseudoplantarum (DSM 20 008) for enzyme production and characterization. d-2-hydroxyisocaproate dehydrogenase could be purified 180-fold starting with 500 g of wet cells.The purification procedure involved liquid-liquid extraction with aqueous two-phase systems and ion-exchange chromatography. At this stage the enzyme has a specific activity of 25 U/mg and can be used for technical applications. Further purification up to a homogeneous protein with a specific activity of 110 U/mg can be achieved by chromatography on Amberlite CG 50 at pH 3.5. Properties important for technical application of the d-HicDH were investigated, especially the substrate specificity and the optimum pH- and temperature ranges for activity and stability of the catalist.     

Conversion of cellulose into fungal cell mass in solid state culture

Summary To satisfy the demand for simple production technology (simple and cheap reactor, cheap recovery and finishing), solid state cultivations were carried out with pretreated straw in a simple fixed bed reactor under nonsterile conditions.The results of these investigations were compared with those evaluated in a stirred tank reactor. The same cell mass fractions were obtained in both reactors. However, about double the cultivation time is necessary for a solid state cultivation as compared to a submerse cultivation.Symbols N₂ nitrogen content of dry biomass (%) - P productivity on cell protein (%/h) - T temperature (°C) - t_F cultivation time (h) - X fungal cell mass fraction (%)     

Interrelation between penicillin productivity and growth rate

Summary Fermentations were carried out in an 801 tower-loop reactor with pellets of Penicillium chrysogenum. The development of the inner structure of the pellets with regard to various fermentation conditions was observed by means of histological preparations of the pellets. Under conditions of energy-source-limitation mycelial tip growth and lysis of other mycelial parts exist simultaneously. Thus the net growth rate (formation rate of cell mass) is higher than the gross growth rate (multiplication rate of cell mass). Under conditions of nitrogen limitation, gross growth rate and net growth rate are identical. A very strict correlation between gross growth rate and penicillin production rate was found as long as sufficient oxygen supply could be maintained and carbon catabolite repression was avoided. The energy source requirement of the biomass can be described with the sum of three terms that correspond to gross growth, lysis compensation growth and maintenance.Symbols a Constant 1/l h - b Constant - K Decay rate constant for product 1/h - K ₁ Substrate inhibition constant g/l - K _op Controls saturation constant for oxygen g/l - K _p Saturation constant for substrate g/l - m Maintenance coefficient 1/h - ms Apparent maintenance coefficient 1/h - O Dissolved oxygen concentration g/l - P Product concentration g/l - p Exponent of O - q Specific productivity 1/h - S Substrate concentration g/l - t Time h - t ₁ Beginning of production phase h - t ₂ Time of pellet dissolution h - V Liquid volume of fermentation broth l - X Dry cell mass concentration g/l - Y Yield of dry cell mass from energy substrate - g Specific gross growth rate of biomass 1/h - l Specific lysis rate of cell mass 1/h - n Specific net growth rate of cell mass 1/h - p Maximum specific rate of product formation 1/h     

Cyclic-AMP-dependent protein kinase type II is associated with the Golgi complex and with centrosomes

The subcellular distribution of the type II enzyme of cAMP-dependent protein kinase (cAMP-dPK II) in epithelial and fibroblastic cells was determined by indirect immunofluorescence microscopy. In interphase cells both regulatory (R II) and catalytic (C) subunits were concentrated in a perinuclear area. By comparison of the R II distribution with the location of a bona fide Golgi membrane constituent, this area was identified as the Golgi complex. The cytochemical localization of R II was confirmed by subcellular fractionation. In addition, cAMP-dPK II was associated with microtubule-organizing centers, in particular with mitotic spindle poles. These distributions of cAMP-dPK II probably represent important factors in mediating the effects of cAMP on basic cellular activities ranging from secretion and proliferation to cell shape and motility.     

Fortpflanzung und entwicklung vonAnemonia sulcata (Anthozoa,Actiniaria) II. Frühentwicklung,Blastula und Gastrula

Early developmental stages of theAnemonia germ are characterized by asynchronously dividing nuclei and an extreme delay of blastomere differentiation. The nuclei migrate to the periphery, whereas nutritive substances remain in the interior. Following this stage, the appearance of cell boundaries results in the formation of the blastoderm and the simultaneous division of the yolk into many fragments. Most of them are exclusively filled with reserve material; only very few contain zooxanthellae or nuclei. On the embryo's surface, conically shaped bundles of long microvilli are obvious. They appear to be less regularly arranged than the spines of oocytes before insemination. Pigment granules that have originated from fusing Golgi vesicles are crowded peripherally in the blastoderm cells. In the nucleoplasm single annulate lamellae that seem to be cut off from the nuclear envelope can frequently be found. There is no further cellular differentiation until gastrulation is completed. Though yolk-containing cellular fragments occupy nearly the whole blastocoel, entoderm formation occurs by invagination. Ultrastructural observations provide evidence of the existence of interstices between entoderm cells that allow all nutritive substances to pass gradually into the gastric cavity. In the region of the blastoporus there are cellular processes enveloping reserve material. Presumably, these observations indicate a so-called filtration of nutritive yolk (Korschelt & Heider, 1909) that might represent an additional mode for the transfer of yolk-containing cellular fragments from blastocoel into gastrocoel.