Fluorescent granules in the guinea-pig hypothalamus and their possible relation to neurosecretory substance

Summary Sections of guinea-pig hypothalamus stained by various methods have been studied under bright-field and fluorescence microscopy to determine the characteristics of refractile granules originally observed in fixed tissue stained for cholinesterases but also seen in unfixed, unstained material.When sections of fresh tissue or tissue fixed in formaldehyde: Na₂SO₄ were examined by fluorescence microscopy, the granules emitted with a wave-length between 600 and 620 m. The density and distribution of the granules closely paralleled that of one of the components that stained with the aldehyde-fuchsin and chrome-alum techniques for neurosecretory substance; granules were absent, however, from the area characterized by Herring substance, and from the stained perikarya and beaded axons of the supraoptic and paraventricular nuclei.The granules were most numerous in the median eminence and infundibular nuclei. Their concentration was about average in mature males and in lactating and hypophysectomized females; they were more abundant in late pregnancy and after ovariectomy and were particularly plentiful some weeks after hysterectomy. They were virtually absent from immature males and females.The possible relation of the granules to releasing factors or to vasotocin-like neurosecretory material is discussed.The authors are most grateful to Dr. J. S. Perry who carried out the surgery involved in these experiments. They also wish to express their thanks to Dr. R. B. Heap who, with Dr. Perry, gave invaluable help in planning the experiments and assessing the data; to Mr. S.P. Mann and Dr. D. F. Sharman for advice on the fluorescence technique and to Miss M. Hamon for skilled technical assistance.Publication of the colour pictures was made possible by a generous grant from the Wellcome Foundation; this support is gratefully acknowledged.Thanks are also due to the University of Alberta for a contribution towards the cost of reprints.     

Some remarks on Rosen's quantum-mechanical approach to genetics

It has been suggested by Robert Rosen (Bull. Math. Biophysics,22, 227–255, 1960) that multiple alleles or pseudoalleles correspond to multiple cites of degenerate states of some quantum mechanical observable which acts as a source of primary genetic information. It is pointed out here that if the quantum mechanical states are determined by the different sequences of the purine and pyrimidine bases in the DNA molecule, the expected number of pseudoalleles would be much too large. The expected number is considerably reduced if we assume that a quantum mechanical state determines the coupling between a molecule of transfer RNA and the corresponding amino acid.     

Cerebral neurosecretory cells and flight in the locust

The effect on flight performance of various superficial lesions of the pars intercerebralis in and around the area of the MNSC (median groups of cerebral neurosecretory cells) have been studied 18 hr after surgery. Only lesions involving areas immediately lateral to the MNSC produce an impairment of flight performance. The release of adipokinetic hormone during flight was studied in these locusts by measuring the changes in haemolymph lipid during flight. It has not been possible to identify any of the areas tested as being concerned with the control of the release of adipokinetic hormone since lipid mobilization was not prevented by any of the operations studied.The poor flight performance in locusts in which the MNSC were destroyed by cautery on day 1 of adult life can be prevented by regular topical application of a synthetic juvenile hormone analogue. It is argued that the effects of removal of the MNSC on the development of flight performance are most likely a consequence of reduced activity of the corpora allata.     

Some remarks on the central nervous system

It is pointed out that the successes obtained in the mathematical biology of the central nervous system are based mostly on a number of more or less complicated neuronic circuit models, each inventedad hoc for the purpose of explaining a given phenomenon. The individual models remain disconnected from each other, however, and the unity of the CNS is not apparent. (Rashevsky,Mathematical Biophysics, 3rd Edition, Vol. II, 1960. New York, Dover Publications, Inc.) Some “field theories” of the CNS, as for example that of Griffith (Bull. Math. Biophysics,25, 111–120, 1963;27, 187–195, 1965), give more expression to this unity but lose in the explanation of specific phenomena. The present paper starts with the picture thatevery neuron in the brain isdirectly or indirectly affected to some extent byevery other neuron. This leads to a system of equations with a very large number of variables. Such a system can be replaced in the limiting case by an integral equation of the first kind. At least two specific results can be obtained with this approach and suggestions for further improvement are made.     

Some remarks on degeneration granules in the genital sphere

Summary By using different methods of staining the authors have made a closer study of the various stages in the process of cell degeneration that take place in the urogenital tract. In the beginning of this cell degeneration the nuclei remnants are Feulgen positive, becoming later, however, Feulgen negative, and accumulating finally into larger conglomerations possessing the same staining-qualities as the cytoplasm.     

Production of antibodies to Manduca sexta cerebral neurosecretory cells

Understanding the neuroendocrine regulation of insect development depends upon having antibody probes to the neurohormones involved, which are usually present at trace levels, making antibody generation difficult. This report describes a simple method for producing antibodies specific to cerebral neurosecretory cells (NSC) of the tobacco hornworm, Manduca sexta, and to the neurohormone(s) they produce. The method involves the isolation of only a few hundred NSC somata (～ 0.3 μg of protein) that serve as the immunogen. The cerebral NSC used were the L-NSC III, the prothoracicotropes, that produce the prothoracicotropic hormone (PTTH), the principal neuroendocrine effector of insect molting and metamorphosis. A PTTH-containing extract of microsurgically isolated somata of the L-NSC III was injected intraperitoneally into a Balb/c mouse. The antiserum produced specifically immunostained the L-NSC III in wholemounts of brains from different developmental stages. This antiserum also contained antibodies directed against PTTH, as shown by its ability to inhibit the neurohormone's biological activity in an in vitro prothoracic gland bioassay. Such antiserum can be used to investigate the ontogeny and phylogeny of NSCs. With the hybridoma technique, monoclonal antibodies to individual NSC proteins (PTTH) could be obtained, circumventing the need to purify them for antibody production. This method should be applicable to comparable neurosecretory cell systems in other insect species.     

Some histochemical reactions on the neurosecretory cells of Rivulogammarus syriacus chevreux (Crustacea, Amphipoda).

The histochemistry of neurosecretory material in neurosecretory cells of Rivulo-gammarus syriacus has been investigated. Histochemically, these cells contain different neurosecretory substances. The material in A and C cells consists of mucopolysaccharides and lipids, that in B, B' and D cells there are a protein containing cystine S-S group, mucopolysaccharides and lipids, and that in E cell contains a weak protein with cystine S-S group, a substance showing beta metachromasia and lipids. The lipids are found in all the cells.     

Fluorescent method for studying the morphogenesis and viability of dermatophyte cells

The dermatophyte Microsporum canis is commonly isolated from human and animal infection. The morphogenesis of this fungus was studied during its developmental stages through the fluorescent method Fluorescein Diacetate and Ethidium Bromide. To this end, 50 l dermatophyte suspension were transferred onto cellophane wrapping esterilized discs (2.5 cm of diameter) placed over the surface of Sabouraud dextrose agar on Petri dishes and incubated at 25 °C for 30 days. Every 60 minutes during the first 24 hours and every 12 hours for next 29 days, one disc was transferred onto glass slide, covered with equal volumes of freshly prepared fluorescein diacetate (FDA) and ethidium bromide (EB) solution, mounted with a coverslip and incubated in the dark for 30 minutes, at 25 °C. Each preparation was then examined on a fluorescent microscope. M. canis presented well defined growth stages: (1) tumescence of cells; (2) germination; (3) development of hyphae; (4) production of conidia and (5) tumescence and formation of arthroconidiae. Using the fluorescent method, non viable cells showed a light bright red coloration and viable cells presented green fluorescence. The principal morphological changes have occurred between the 3rd until the 18th day of culture. The method is very useful to demonstrate the dermatophyte growth stages as well as the perfect differentiation between viable and non viable cells.This revised version was published online in October 2005 with corrections to the Cover Date.     

Some remarks on the Kedem-Katchalsky equations for non-electrolytes

The Kedem-Katchalsky equation for the flow of a non-electrolyte through a homogeneous membrane is shown to be a first order expansion of an exact integral of the Spiegler-Bearman-Kirkwood frictional equations under the assumption that the partial frictional coefficients, ζ _ij , are concentration independent. The equations are solved in terms of volume flow; there are no water-to-volume flow correction terms for the permeability, ω, or the reflection coefficient, σ. The precision of the expansion depends upon the magnitude of the water flow. The frictional coefficientsf _sm andf _sw are given as functions of the experimentally determined parameters ω and σ; the frictions, are shown to be independent ofL _p .