Effect of neurectomy on nuclease activity in skeletal muscles of rats

Author followed up the activity of the three enzymes involved in the catabolism of nucleic acids--acid deoxyribonulease (DNase II), alkaline ribonuclease (RNase I), and acid ribonuclease (RNase II)--in the denervated gastrocnemius and soleus muscles of rats for 28 postoperative days. The activity of both acid nucleases increased in both types of denervated muscles, compared with the respective controls. Up to the 14th postoperative day, the activity excess of both acid nucleases was more significant in the m. gastrocnemius than in the m. soleus. The RNase I ran below the control activity during the whole period in the m. soleus and up to the 14th day in the m. gastrocnemius. The role of nucleases and nuclease inhibitors in the changes of nucleic acid catabolism in neurogenic muscular atrophies is discussed.     

Dual translational initiation sites control function of the lambda S gene.

Lysis gene S of phage lambda has a 107 codon reading frame beginning with the codons Met1-Lys2-Met3. Genetic data have suggested that translational initiation occurs at both Met1 and Met3, generating two polypeptides, S107 and S105 respectively. We have proposed a model in which the proper scheduling of lysis depends on the partition of translational initiations between the two start codons. Here, using in vitro methods, we show that two stem-loop structures, one immediately upstream of the reading frame and a second approximately 10 codons within the gene, control the partitioning event. Utilizing primer-extension inhibition or 'toeprinting', we show that the two S start codons are served by two adjacent Shine-Dalgarno sequences. Moreover, the timing of lysis supported by the wild-type and a number of mutant alleles in vivo can be correlated with the ratio of ternary complex formation over Met1 and Met3 in vitro. Thus the regulation of the S gene is unique in that the products of two adjacent in-frame initiation events have opposing function.     

Cellular regulation of ADP-ribosylation of proteins. III. Selective augmentation of in vitro ADP-ribosylation of histone H3 in murine thymic cells after in vivo emetine treatment

Thymic cells were isolated at intervals of between 0 and 144 h from mice that received one intraperitoneal injection of emetine (33 mg/kg), and thymus weight, incorporation of [14C]leucine into proteins and [3H]thymidine into DNA in intact thymic cells, as well as initial rates of protein ADP-ribosylation in permeabilized cells [A. Sóoki-Tóth, F. Asghari, E. Kirsten, and E. Kun (1987) Exp. Cell Res. 170, 93] were simultaneously monitored. The effect of emetine as an inhibitor of protein synthesis [F. Antoni, N. G. Luat, I. Csuka, I. Oláh, A. Sóoki-Tóth, and G. Bánfalvi (1987) Int. J. Immunopharmacol. 9, 333] corresponds to the induction of sequential cellular events, such as cell exit and remigration, by other antimitotic agents [C. Penit and F. Vasseur (1988) J. Immunol. 140, 3315] and produces an activation of proliferation of cells reentering into this organ. Proliferation, as demonstrated by a large increase in DNA synthesis and entrance into S phase, was kinetically related to an apparent increase in poly(ADP-ribose) polymerase activity in thymic cells and a highly significant in vitro ADP-ribosylation of histone H3. Since no DNA fragmentation occurred in thymic cells, as tested by a fluorometric technique [C. Birnboim and J. J. Jevac (1981) Cancer Res. 41, 1889], it is probable that a selective activation of poly(ADP-ribose) polymerase may have been induced in cells that undergo differentiation and proliferation while repopulating the thymus.     

No effect of isolation on blood pressure and daily electrolyte excretion in rats

The effects of isolation stress on mean blood pressure (BP) and on body weight, water and food intake as well as on urine flow, urinary sodium and potassium excretion were studied in CFY and Long Evans rats. During a 7 day isolation period, food and water intake as well as urine flow, urinary sodium and potassium excretion, as expressed for 100 g body weight, were not changed in either group. Body weight increased similarly in isolated (38 +/- 2 g) and aggregated (41 +/- 5 g) CFY rats. Compared to group housed rats, BP in male CFY animals was not increased after a 7 day isolation (111 +/- 3 vs 111 +/- 3 mmHg, NS). In additional experiments high sodium intake by physiological saline drinking slightly elevated blood pressure but failed to induce arterial hypertension in isolated rats (118 +/- 2 vs 121 +/- 3 mmHg, NS). We conclude that, contrary to some reports from other laboratories, isolation stress has no detectable effect on BP and/or water and electrolyte balance.     

Time course of denervation diuresis and natriuresis in the anaesthetized rat

The effect of unilateral renal sympathectomy on renal excretion of water and sodium was studied in three groups of Inactin-anaesthetized rats: 1-3, 4-19, and 20-35 weeks after denervation. Increased sodium excretion from the denervated kidney in the absence of changes in GFR was observed up to 35 weeks following renal denervation. Thus, in a functional sense, renal reinnervation may have only been partial during the time interval studied.     

In vitro fertilization with normal development in the sheep

Ovine tubal (n = 87) and ovarian in vitro matured oocytes (n = 99) were fertilized in vitro with ejaculated spermatozoa capacitated for 8 h in modified defined medium buffered with Hepes. High levels of fertilization were obtained as assessed by development to two-to six-cell stage within 40 h (75. 8% for ovulated and 62. 6% for in vitro matured oocytes). Electron microscope analysis of oocytes 20–22 h after insemination indicated that in vitro fertilization approximated the in vivo events. Embryos (two- to six-cell) were transferred surgically to the oviducts of pseudopregnant rabbits. Three days later, 42 (from ovulated oocytes) and 15 (from in vitro matured oocytes) embryos were recovered; 26 (61. 9%) and 10 (66. 6%), respectively, had cleaved at least once. Embryos incubated in vivo (n = 20 from ovulated oocytes; n = 9 from in vitro matured oocytes) were transferred surgically to the uteri of seven and four recipient ewes resulting in four and two pregnancies, respectively, from which three and one, respectively, have been maintained ( > 3 months). The first lamb resulting from the in vitro fertilization of an ovulated oocyte was born. In addition, six embryos (two- to four-cell) from tubal oocytes and ten embryos (two- to six-cell) from in vitro matured oocytes were directly transferred to the oviducts of two and three ewes, respectively. Two pregnancies resulting from in vitro matured fertilized oocytes are in progress ( > 3 months).     

CD and Fourier transform ir spectroscopic studies of peptides. II. Detection of β-turns in linear peptides

Comparative CD and Fourier transform ir (FTIR) spectroscopic data on N-Boc protected linear peptides with or without the (Pro-Gly) β-turn motif (e.g., Boc-Tyr-Pro-Gly-Phe-Leu-OH and Boc-Tyr-Gly-Pro-Phe-Leu-OH) are reported herein. The CD spectra, reflecting both backbone and aromatic contributions, were not found to be characteristic of the presence of β-turns. In the amide I region of the FTIR spectra, analyzed by self-deconvolution and curve-fitting methods, the β-turn band shewed up between 1639 and 1633 cm^?1 in trifluoroethanol (TFE) but only for models containing the (Pro-Gly) core. This band war-also present in the spectra in chloroform but absent in dimethylsulfoxide. These findings, in agreement with recent ir data on cyclic models and 3₁₀-helical polypeptides and protein in D₂O [see S. J. Prestrelski, D. M. Byler, and M. P. Thompson (1991), International Journal of Peptide and Protein Research, Vol. 37, pp. 508–512; H. H. Mantsch, A. Perczel. M. Hollósi, and G. D. Fasman (1992), FASEB Journal, Vol. 6, p. A341; H. H. Mantsch. A. Perczel, M. Hollósi, and G. Fasman (1992), Biopolymers. Vol. 33, pp. 201–207; S. M. Miick, G. V. Martinez, W. R. Fiori, A. P. Tedd, and G. L. Millhauser (1992). Nature, Vol. 359, pp. 653–655], suggest that the amide I band, with a major contribution from the acceptor C ? O of the 1 ← 4 intramolecular H bond of β-turns, appears near or below 1640 cm^?1, rather than above 1660 cm^?1. In TFE, bands between 1670 and 1660 cm^?1 are mainly due to “free” carbonyls, that is, C ? O's of amides that are solvated but not involved in the characteristic H bonds of periodic secondary structures or β-turns. © 1994 John Wiley & Sons, Inc.     

Are brood sex ratios adaptive?—The effect of experimentally altered brood sex ratio on nestling growth,mortality and recruitment

Brood sex ratios (BSRs) have often been found to be nonrandom in respect of parental and environmental quality, and many hypotheses suggest that nonrandom sex ratios can be adaptive. To specifically test the adaptive value of biased BSRs, it is crucial to disentangle the consequences of BSR and maternal effects. In multiparous species, this requires cross-fostering experiments where foster parents rear offspring originating from multiple broods, and where the interactive effect of original and manipulated BSR on fitness components is tested. To our knowledge, our study on collared flycatchers (Ficedula albicollis) is the first that meets these requirements. In this species, where BSRs had previously been shown to be related to parental characteristics, we altered the original BSR of the parents shortly after hatching by cross-fostering nestlings among trios of broods and examined the effects on growth, mortality and recruitment of the nestlings. We found that original and experimental BSR, as well as the interaction of the two, were unrelated to the fitness components considered. Nestling growth was related only to background variables, namely brood size and hatching rank. Nestling mortality was related only to hatching asynchrony. Our results therefore do not support that the observed BSRs are adaptive in our study population. However, we cannot exclude the possibility of direct effects of experimentally altered BSRs on parental fitness, which should be evaluated in the future. In addition, studies similar to ours are required on various species to get a clearer picture of the adaptive value of nonrandom BSRs.