Action Selection and Flexible Switching Controlled by the Intralaminar Thalamic Neurons

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Clerodane diterpene glucosides from Tinospora rumphii

Seven new diterpene glucosides of the clerodane type were isolated from the stems of Tinospora rumphii. Among the seven, one was isolated as an acetyl derivative. The structures of these compounds were established by the application of various spectroscopic techniques.     

Synthesis of phenylalanine and production of other related compounds from phenylpyruvic acid and phenylacetic acid by ruminal bacteria,protozoa, and their mixture in vitro

Phenylalanine (Phe) synthesis and the production of other related compounds by mixed ruminal bacteria (B), protozoa (P), and a combination of the two mixture (BP) in an in vitro system were quantitatively investigated using phenylpyruvic acid (PPY) and phenylacetic acid (PAA) as substrates. Rumen microorganisms were collected from fistulated goats fed lucerne cubes (Medicago sativa) and a concentrated mixture twice a day. Microbial suspensions were anaerobically incubated at 39 degrees C for 12 h. Phe and some other related compounds in both supernatants and microbial hydrolysates of the incubations were analysed by HPLC. A large quantity of Phe was produced from both PPY and PAA not only in B but also in P. In B suspensions, free Phe also accumulated in the medium only when PPY was used as a substrate. The ability of B to synthesize Phe from both PPY and PAA (expressed as unit 'per microbial nitrogen') was 5.1 and 24.8% higher than P, respectively. Phe production from PPY in B and P was 43.5 and 55.2% higher than that from PAA. Large amounts of PAA (17-27%) were produced from PPY in all microbial suspension and production amounts were similar in B and P. Small amounts of benzoic acid (BZA) were produced from PPY and PAA in B, P, and BP, and higher BZA production was observed in P as compared to B. Phenylpropionic acid (PPR) was produced in B from both PPY and PAA, but not in P or BP. A trace amount of phenyllactic acid (PLA) was detected only from PPY in B. Higher concentrations of an unknown compound from PPY and PAA were found to be accumulated in the body protein of B and also in the medium of P, and production of the compound from both PPY and PAA was also higher in B than P.     

In vitro metabolism of phenylalanine by ruminal bacteria,protozoa, and their mixture

An in vitro study was conducted to examine the metabolism of phenylalanine (Phe) by mixed rumen bacteria (B), mixed rumen protozoa (P), and a combination of the two (BP). Rumen microorganisms were collected from fistulated goats fed lucerne cubes (Medicago sativa) and a concentrated mixture twice a day. Microbial suspensions were anaerobically incubated at 39 degrees C for 12 h. Phe and some other related compounds in both supernatants and microbial hydrolysates of the incubations were analysed by HPLC. The net degradation rate (&mgr;mol/g microbial nitrogen) of Phe in B was about 1.5-fold higher than that in P. Phe was converted mainly into phenylacetic acid (PAA) and unknown compound(s) that presumably involved tyrosine in B, P, and BP during the 12 h incubation period. Small amounts of benzoic acid (BZA), and traces of phenylpropionic acid (PPR) and phenyllactic acid (PLA) were also produced from Phe. PAA production in B was found to be higher than that in P, whereas it was significantly higher in BP. Although BZA production was less than one-tenth that of PAA production, it was higher in P than in B and BP. PPR was detected in both B and BP, but not in P. PLA was detected only in B. The production of unknown compound(s) was higher in B than in P and BP.     

Comprehensive pyrosequencing analysis of the bacterial microbiota of the skin of patients with seborrheic dermatitis

Seborrheic dermatitis (SD) is a chronic inflammatory dermatologic condition in which erythema and itching develop on areas of the body with sebaceous glands, such as the scalp, face and chest. The inflammation is evoked directly by oleic acid, which is hydrolyzed from sebum by lipases secreted by skin microorganisms. Although the skin fungal genus, Malassezia, is thought to be the causative agent of SD, analysis of the bacterial microbiota of skin samples of patients with SD is necessary to clarify any association with Malassezia because the skin microbiota comprises diverse bacterial and fungal genera. In the present study, bacterial microbiotas were analyzed at non‐lesional and lesional sites of 24 patients with SD by pyrosequencing and qPCR. Principal coordinate analysis revealed clear separation between the microbiota of non‐lesional and lesional sites. Acinetobacter, Corynebacterium, Staphylococcus, Streptococcus and Propionibacterium were abundant at both sites. Propionibacterium was abundant at non‐lesional sites, whereas Acinetobacter, Staphylococcus and Streptococcus predominated at lesional sites; however, the extent of Propionibacterium colonization did not differ significantly between lesional and non‐lesional sites according to qPCR. Given that these abundant bacteria hydrolyze sebum, they may also contribute to SD development. To the best of our knowledge, this is the first comprehensive analysis of the bacterial microbiotas of the skin of SD patients.     

The roles of RNA polymerase and RNAase I in stable RNA degradation in Escherichia coli carrying the srnB+ gene

In Escherichia coli cells carrying the srnB⁺ gene of the F plasmid, rifampin, added at 42°C, induces the extensive rapid degradation of the usually stable cellular RNA (Ohnishi, Y., (1975) Science 187, 257–258; Ohnishi, Y., Iguma, H., Ono, T., Nagaishi, H. and Clark, A.J. (1977) J. Bacteriol. 132, 784–789). We have studied further the necessity for rifampin and for high temperature in this degradation. Streptolidigin, another inhibitor of RNA polymerase, did not induce the RNA degradation. Moreover, the stable RNA of some strains in which RNA polymerase is temperature-sensitive did not degrade at the restrictive temperature in the absence of rifampin. These data suggest that rifampin has an essential role in the RNA degradation, possibly by the modification of RNA polymerase function. A protein (M_r 12 000) newly synthesized at 42°C in the presence of rifampin appeared to be the product of the srnB⁺ gene that promoted the RNA degradation. In a mutant deficient in RNAase I, the extent of the RNA degradation induced by rifampin was greatly reduced. RNAase activity of cell-free crude extract from the RNA-degraded cells was temperature-dependent. The RNAase was purified as RNAase I in DEAE-cellulose column chromatography and Sephadex G-100 gel filtration. Both in vivo and with purified RNAase I, a shift of the incubation mixture from 42 to 30°C, or the addition of Mg²⁺ ions, stopped the RNA degradation. Thus, an effect on RNA polymerase seems to initiate the expression of the srnB⁺ gene and the activation of RNAase I, which is then responsible for the RNA degradation of E. coli cells carrying the srnB⁺ gene.     

Two coupled oscillators as a model for the coordinated finger tapping by both hands

Recently, it was found that rhythmic movements (e.g. locomotion, swimmeret beating) are controlled by mutually coupled endogeneous neural oscillators (Kennedy and Davis, 1977; Pearson and Iles, 1973; Stein, 1974; Shik and Orlovsky, 1976; Grillner and Zangger, 1979). Meanwhile, it has been found out that the phase resetting experiment is useful to investigate the interaction of neural oscillators (Perkel et al., 1963; Stein, 1974). In the preceding paper (Yamanishi et al., 1979), we studied the functional interaction between the neural oscillator which is assumed to control finger tapping and the neural networks which control some tasks. The tasks were imposed on the subject as the perturbation of the phase resetting experiment. In this paper, we investigate the control mechanism of the coordinated finger tapping by both hands. First, the subjects were instructed to coordinate the finger tapping by both hands so as to keep the phase difference between two hands constant. The performance was evaluated by a systematic error and a standard deviation of phase differences. Second, we propose two coupled neural oscillators as a model for the coordinated finger tapping. Dynamical behavior of the model system is analyzed by using phase transition curves which were measured on one hand finger tapping in the previous experiment (Yamanishi et al., 1979). Prediction by the model is in good agreement with the results of the experiments. Therefore, it is suggested that the neural mechanism which controls the coordinated finger tapping may be composed of a coupled system of two neural oscillators each of which controls the right and the left finger tapping respectively.     

Involvement of proliferating cell nuclear antigen (cyclin) in DNA replication in living cells.

Proliferating cell nuclear antigen (PCNA) (also called cyclin) is known to stimulate the activity of DNA polymerase delta but not the other DNA polymerases in vitro. We injected a human autoimmune antibody against PCNA into unfertilized eggs of Xenopus laevis and examined the effects of this antibody on the replication of injected plasmid DNA as well as egg chromosomes. The anti-PCNA antibody inhibited plasmid replication by up to 67%, demonstrating that PCNA is involved in plasmid replication in living cells. This result further implies that DNA polymerase delta is necessary for plasmid replication in vivo. Anti-PCNA antibody alone did not block plasmid replication completely, but the residual replication was abolished by coinjection of a monoclonal antibody against DNA polymerase alpha. Anti-DNA polymerase alpha alone inhibited plasmid replication by 63%. Thus, DNA polymerase alpha is also required for plasmid replication in this system. In similar studies on the replication of egg chromosomes, the inhibition by anti-PCNA antibody was only 30%, while anti-DNA polymerase alpha antibody blocked 73% of replication. We concluded that the replication machineries of chromosomes and plasmid differ in their relative content of DNA polymerase delta. In addition, we obtained evidence through the use of phenylbutyl deoxyguanosine, an inhibitor of DNA polymerase alpha, that the structure of DNA polymerase alpha holoenzyme for chromosome replication is significantly different from that for plasmid replication.