On the existence and separation of the follicle stimulating hormone releasing hormone from the luteinizing hormone releasing hormone.

Porcine hypothalamic fragments were extracted by 2M AcOH at 4°C, and the extractives were subsequently processed in the presence of one protease inhibitor and one anti-oxidant. Gel filtration was performed on Bio-Gel P-2, and supplementary [³H]-LHRH and [¹⁴C]- 3H]-LHRH, and was differentiated from [¹⁴C]- 相似文献   

Fractionation of constituents of ribonucleoproteins containing heterogeneous nuclear ribonucleic acid.

A method of fractionation of hnRNP constituents adaptable to large-scale preparation is presented. It is based on differential resistance to salt dissociation of the two classes of units of hnRNP, the 30--50S monoparticles and the heterogeneous complexes. The monoparticle proteins were released from hnRNP by 0.4 M NaCl. They were separated from the salt-resistant RNP corresponding to the heterogeneous complexes in three steps: chromatography on DEAE-cellulose, high-speed centrifugation, and Bio-Gel chromatography. The latter chromatography permitted a first fractionation of monoparticle proteins according to molecular weight. Such fractions may serve for purification of individual proteins of molecular weight below 80 000. After the two first steps, two fractions of salt-resistant RNP were obtained. In addition to heterogeneous RNA up to 30 S, small nuclear RNAs were detected which represented 6% of total RNA. The protein pattern was complex, and no clear-cut segregation of groups of proteins could be observed between the two fractions. They were both highly enriched in phosphoproteins as compared to nomoparticle proteins. In another fraction corresponding to the void volume of Bio-Gel chromatography, one-third of the RNA was small nuclear RNA. It is suggested that this fraction contains snRNP in addition to free proteins of molecular weight above 80 000 and to salt-resistant RNP similar to those described above but of small size.     

Spatial and temporal patterns of temperature,alkalinity, dissolved oxygen and conductivity in an oligo-mesotrophic,deep-storage reservoir in central Texas

Impoundment behavior was determined for alkalinity, temperature, dissolved oxygen, and conductivity from stations located along the length of a bottom-draining, oligo-mesotrophic, hardwater, deep-storage reservoir located in central Texas. The epilimnion deepened the length of the reservoir throughout the summer as a result of drawdown. Bicarbonate alkalinity and conductivity exhibited both longitudinal and vertical stratification. Alkalinity and conductivity in the epilimnion decreased from the riverine reach downreservoir to the dam. This longitudinal progression was attributed to inflow and photosynthetically induced epilimnetic decalcification.Hypolimnetic anoxic conditions first occurred in the sedimentation zone in the upreservoir and riverine reaches and then developed in a downreservoir pattern as summer progressed as a result of drawdown. Alkalinity and conductivity in the hypolimnion increased during anoxic conditions and consequently increased in a downreservoir progression.     

Bacterial breakdown of benomyl. II. Mixed cultures

Experiments with mixed bacterial cultures grown in liquid media which contained the benzimidazole fungicide benomyl, with or without Na-lactate, as source of carbon provided circumstantial evidence for cleavage of the benzimidazole heterocyclic ring. Yet, neither 2-aminobenzimidazole (2-AB) nor benzimidazole, as sole source of carbon, supported any bacterial growth. Total ¹⁴C-balance analysis experiments conclusively showed production of ¹⁴CO₂ from [2-¹⁴C] methyl benzimidazol-2-yl carbamate (MBC), and thus cleavage of the benzimidazole nucleus; bioassays, however, showed that the actual rate of benomyl and MBC breakdown was only small, the parent compound benomyl being still recovered in substantial quantities after up to 80 days of incubation. Therefore, cleavage of the benzimidazole ring is probably a matter of cometabolism, n-butylamine which originates from the butylcarbamoyl side chain serving as the proper source of carbon.Besides radiolabelled 2-AB and CO₂, an unknown metabolite was isolated which showed characteristics of a 2-AB-nucleotide. Probably, 2-AB was incorporated into bacterial DNA, which upon lysis of the bacterial cells gave rise to the nucleotide in question. Therefore, 2-AB might exert its inhibitory action by interfering with the normal functioning of DNA.     

On the relation between filament overlap and the number of calcium-binding sites on glycerinated muscle fibers.

The formation of rigor complexes between the thick and thin filaments of glycerinated rabbit psoas muscle fibers causes the fibers to bind more calcium at any given level of free calcium. I studied the maximum amount of calcium bound as a function of filament overlap under rigor conditions. Fibers stretched to zero filament overlap (sarcomere length greater than 3.8 micron) bound exactly 75% as much calcium as fibers with maximum overlap. Between these extremes a linear relationship was found between maximum bound calcium and the length of the overlap zone. The results support the hypothesis that in the intact filament lattice one of the four calcium-binding sites of troponin depends for its existence on attachment between myosin and actin. In addition, the linear relation between maximum bound calcium and filament overlap is consistent with the assumption that the cooperative effect of rigor complex formation on calcium binding is limited to the binding site in the immediate vicinity of the rigor complex.     

The active species of 'CO2' utilized by reduced ferredoxin:CO2 oxidoreductase from Clostridium pasteurianum.

Reduced ferredoxin:CO2 oxidoreductase (CO2 reductase) from Clostridium pasteurianum catalyzes the reduction of 'CO2' to formate with reduced ferredoxin, an isotopic exchange between 'CO2' and formate in the absence of ferredoxin, and the oxidation of formate to 'CO2' with oxidized ferredoxin. The active species of 'CO2', i.e. CO2 or HCO3 (H2CO3), utilized by the enzyme was determined. The method employed for the species identification was that of Copper et al. (1968). Both 'CO2' reduction to formate and the exchange reaction were studied. Data were obtained which are compatible with those expected if CO2 is the active species. The V and the dissociation constant Ks of the enzyme - CO2 complex in dependence of pH were determined from initial velocity studies of the exchange reaction. V was found to be only slightly affected by pH between 5.5 and 7.5. Ks was markedly dependent on pH; the constant increased with decreasing pH from 0.2 mM at pH 7.5 to 3 mM at pH 5.5.     

Postischaemic circulation disturbances.

Restoration of blood supply after ischaemic conditions in extremities and testes is inhibited by reversible intravasal aggregation of erythrocytes. This process is promoted by the increased permeability of the capillaries associated with the formation of oedema and the entailing increase of the haematocrit. For overcoming the stasis the increased structural viscosity caused by the aggregation of erythrocytes requires an increase in pressure as a starter effect which is not achieved by the flow pressure at once everywhere. Intravenously administered particles of Indian ink mark the formation and dissolution of aggregates. Even areas with originally normal blood supply may be obstructed by the later formation of aggregates. Thrombi on the walls of arterial and venous vessels and other lesions of the intima do not sufficiently explain the disturbance of perfusion. Oedema and extravasating leucocytes are found in the microcirculation. The parenchyma to be supplied shows formation of necrosis.