Muscle fibrillation caused by cytochalasin-B applied to the motor nerve.

Cytochalasin-B, a drug known to interfere with axoplasmic transport, evoked fibrillary potentials in the geniohyoid muscle when applied to its motor nerve. Despite this denervation-like effect, neuromuscular transmission remained normal. Some contractile characteristics of the muscle were studied. It was found that contraction time, isometric twitch tension, and half-relaxation time were not altered by the drug treatment. The present findings show that neurogenic molecular factors conveyed by axoplasmic transport to the nerve terminal are involved in the regulation of some muscle membrane characteristics but do not modify the muscle contractile features.     

Cross-links in African swine fever virus DNA.

African swine fever virus DNA sediments in neutral sucrose density gradients as a single component with a sedimentation coefficient of 60S. In alkaline sucrose density gradients, this material shows two components with sedimentation coefficients of 85S and 95S, respectively. The sedimentation rate value of alkali-denatured virus DNA in neutral sucrose density gradients and the renaturation velocity of denatured DNA show that is reassociated much faster than expected from its genetic complexity. This behavior is compatible with the existence of interstrand cross-links in the molecule. We also present results which suggest that there are only a few such cross-links per molecule, that they are sensitive to S1 nuclease digestion, and that they are probably located next to the ends of the DNA.     

The arrangement of nucleotides in the coding regions of natural templates

Summary The relation of the nucleotide sequences in the coding regions of natural templates and of the short nucleotide sequence in 3 terminus of 16 S ribosomal RNA was found to differ from random pattern. The observation is interpreted in terms of both the ribosomal interactions and the molecular evolution.     

An autecological study of Palicourea riparia Bentham as related to rain forest disturbance in Puerto Rico

Summary The present study is an attempt to understand biology of Palicourea riparia Bentham relative to the process of recovery following disturbance in a tropical rain forest in Puerto Rico. In this species seed germination and seedling maintenance are favored by environmental conditions associated with disturbance, yet germination and seedling persistence are significant in undisturbed forest conditions. The pattern of seed germination indicates that (1) the seeds possess a dormancy mechanism, (2) dormany is not evenly distributed within a seed population, and (3) some seeds can remain viable if buried in the soil for at least three years. Results from reciprocal transplant studies indicate that there has been no differentiation into growth ecotypes in this species. Photosynthetic rates are very low under both field and laboratory conditions. In the laboratory, photosynthetic rates are consistently enhanced by increases in light intensity. It is concluded that P. riparia is a species of wide ecological amplitude that acts as a gap opportunist.     

Effects of abscisic acid,gibberellic acid and fusicoccin on the transmembrane potential during the early phases of germination in radish (Raphanus sativus L.) seeds

During germination, the transmembrane electric potential (PD) of cortical cells of the embryonal axis of radish seeds (Raphanus sativus L.) rises from-120 mV initially to a maximum of-150 mV after 5 h incubation, then falls again to stable values of around-120 mV. Treatments inhibiting germination block the transitory PD increase. Administration of uncoupling agents or low temperatures, during the process of germination, produces a marked fall of the PD transitory increase. Abscisic Acid has a parallel inhibitory effect on PD and germination, while fusicoccin produces a rise in both; administration of abscisic acid with fusicoccin inhibits germination, while the PD remains at the high levels given by fusicoccin. These results are discussed in relation to ion exchange at membrane level.Abbreviations ABA abscisic acid - FC fusicoccin - GA₃ gibberellic acid - PD electric potential difference (between the vacuole and the external medium) - CH cycloheximide - DNP dinitrophenol - FCCP (p-trifluormethoxy)-carbonylcyanide-phenylhydrazone - DCCD N,N-dicyclohexylcarbodiimide     

Sympathetic control on salivary secretion by the parotid gland in rabbit. I. Effects on the unstimulated gland (author's transl)]

The sympathetic influences on the rabbit unstimulated parotid gland were studied. The experiments were carried out in anaesthetized rabbits with the Stenon aduct cannulated. Direct stimulation of the superior cervical ganglion elicits variable salivary flows. The high amylase content in the saliva points to a sympathetic secretory action upon acinar cells. The administration of alpha-adrenergic blocking agents (dihydroergotamine, phentolamine and phenoxybenzamine) clearly reduces and even abolishes the effect of the sympathetic stimulation upon flow. The administration of a beta-adrenergic blocking agent (propranolol) slightly reduces the sympathetic action. However the amylase activity is greatly reduced. All this suggests that the secretory effects on the fluid fraction should predominantly be alpha-adrenergic while on the secretion of enzymes the beta-receptors should play an important role.     

A family with a satellited Yq chromosome

Summary A large pedigree with a satellited Yq chromosome is described, Q, C, and NOR banding were performed. Family C proband suffers from a Klinefelter syndrome.     

Frequency and types of induced and spontaneous chromosome aberrations in relation to cell kinetics

Summary Induced and spontaneous structural chromosome aberrations (SCA) were studied in a child accidentally radiated with a high dose of ¹⁹²Ir, and in three sibs with Fanconi's anemia, analyzing by separate first division metaphases (FDM) and second division metaphases (SDM). The results showed that the number of SCA, number of cells with aberrations, and SCA per cell were markedly higher in FDM in all patients.Furthermore, for some type of structural changes like dicentric chromosomes and chromatid interchanges, the differences were particularly striking. The importance of ascertaining FDM identified with proper techniques, for the study of the clastogenic effect of environmental agents and some aspects related to the differences in cytogenetic features found in diverse tissues in Fanconi's anemia are discussed.     

Retinoblastoma,gross internal malformations,and deletion 13q14→q31

Summary A male patient with an interstitial deletion 13q14q31 is described. Our necropsy findings included a left retinoblastoma and several gross internal malformations. In this paper we reaffirm that band 13q14 is involved in cases of retinoblastoma and we propose, after studying accompanying cases of total or partial long arm trisomies 13, that the loss of specific 13q bands, from 13q14 to 13q31 is responsible for the congenital defects we are describing.     

The deafness,onycho-osteo-dystrophy,mental retardation syndrome

Summary Two new cases of the D.O.O.R. syndrome are reported. The patients described showed most of the characteristics described by Cantwell (1975) and some others that may represent additional clinical findings of this rare syndrome.