bluuebunny/crossref_metadata_2025_split huggingface dataset:
Localization of human growth hormone to a sub-set of cytoplasmic vesicles in transfected PC12 cells
Authors: Schweitzer Erik S. , Paddock Stephen 
Published: April 2021

ABSTRACT
Two distinct population of vesicles can be identified in PC 12 cells by subcellular fractionation and immunofluorescence. Density gradient separation reveals one population of dense vesicles that contains the transgenic regulated secretory protein hGH (human growth hormone) along with the endogenous neurotransmitter norepinephrine. Some of the neuronal vesicle marker synaptophysin (P38) is also associated with these vesicles. A second population of low-density vesicles contains synaptophysin but not hGH or norepinephrine. Immunofluorescence localization of hGH revealed a pattern consistent with packaging into catecholaminergic vesicles: the staining is punctate and most concentrated in the tips of the neuritic processes, with secondary accumulation in the perinuclear region. Double-staining of cells for hGH and synaptophysin confirms that these proteins do not co-localize but rather are spatially segregated within the cell. The observed distribution of vesicle markers is inconsistent with simple models for the generation of one type of vesicle from the other, suggesting that the vesicles are products of two divergent biosynthetic pathways. While the hGH is clearly contained in regulated secretory vesicles, the function of the second population of vesicles remains uncertain.
Lysosomal enzyme secretory mutants of Dictyostelium discoideum
Authors: Ebert David L. , Jordan Kevin B. , Dimond Randall L. 
Published: April 2021

ABSTRACT
Dictyostelium discoideum secretes a number of lysosomal enzymes during axenic growth and upon suspension in a low ionic strength, non-nutrient buffer (standard secretion conditions). These secretory characteristics have allowed us to identify 74 lysosomal enzyme secretory mutants generated by N-methyl-N′ -nitro-N-nitrosoguanidine mutagenesis. The majority of these mutants fell into one of four classes, on the basis of their secretory characteristics in non-nutrient buffer. The four mutant classes indicate that a minimum of three distinct sets of genes are necessary for proper secretion of lysosomal enzymes from D. discoideum cells under standard secretion conditions: one set of genes that is involved in general lysosomal enzyme secretion, one that is involved in glycosidase type secretion, and a third that is involved in acid phosphatase type secretion. These three classes likely reflect heterogeneity in the intracellular destination of lysosomal enzymes, the secretory mechanism, or both. A fourth set of genes may be necessary for proper secretion during growth, but plays no role under standard secretion conditions. These are likely altered in the regulation of secretion or in lysosomal enzyme targeting. Of the 74 secretory mutants, 36 were also modification mutants resulting in decreased pl, thermolability, or in vivo instability of lysosomal enzyme activities. The high frequency of modification mutants indicates an integral relationship between lysosomal enzyme modification, and lysosomal enzyme targeting and secretion in D. discoideum.
Microtubule depolymerization inhibits transport of cathepsin D from the Golgi apparatus to lysosomes
Authors: Scheel Jochen , Matteoni Raffaele , Ludwig Thomas , Hoflack Bernard , Kreis Thomas E. 
Published: April 2021

ABSTRACT
Lysosomes as well as a prelysosomal compartment rich in the mannose 6-phosphate receptor are clustered close to the Golgi apparatus in the perinuclear region of the microtubule organizing center in interphase human skin fibroblasts. The spatial organization of these organelles depends on an intact microtubule network. Depolymerization of the microtubules by treatment of cells with nocodazole leads to random scattering of Golgi elements, the prelysosomal compartment, and lysosomes throughout the cytoplasm. To test whether microtubules and the spatial organization of these organelles are important for efficient transport of lysosomal enzymes, the effect of microtubule depolymerization on the maturation of newly synthesized cathepsin D was studied. An up to fivefold inhibition of proteolytic maturation of cathepsin D was observed in drug-treated cells. This effect was due to a decreased rate of transport of cathepsin D from the Golgi apparatus to lysosomes. Depolymerization of microtubules did not inhibit transport of cathepsin D from the endoplasmic reticulum to the trans-Golgi network. Furthermore, synthesis of the phosphomannosyl marker present on cathepsin D was not affected by nocodazole. These results suggest that efficient transport of cathepsin D from the Golgi apparatus to a prelysosomal compartment and lysosomes is facilitated by microtubules and the spatial organization of these organelles.
Extracts from eggs and oocytes of Xenopus Laevis differ in their capacities for nuclear assembly and dna replication
Authors: Cox Lynne S. , Leno Gregory H. 
Published: April 2021

ABSTRACT
We describe a cell-free extract derived from the oocytes of Xenopus laevis. The oocyte extract is capable of decondensing sperm chromatin and of replicating single-stranded DNA in a semiconservative, aphidicolin-sensitive manner. In addition, oocyte extract supports the elongation phase of DNA synthesis in nuclei that have been preinitiated for replication. All of these properties are shared by previously described egg extracts.
However, oocyte extracts differ from egg extracts in two important ways. First, they cannot support nuclear assembly, as visualised by phase-contrast, fluorescence and electron microscopy. Second, they do not initiate replication on chromatin or nuclei de novo. Crude low-speed supernatants can be partially fractionated into soluble and vesicular components by high-speed centrifugation. Such fractions from eggs can be functionally reconstituted, but the oocyte soluble fraction does not acquire the ability to assemble nuclei, or replicate them, even when supplemented with the egg vesicular fraction. Similarly, oocyte vesicles cannot substitute for egg vesicles on reconstitution with the egg soluble fraction. When the requirement for nuclear assembly is bypassed by using preformed, quiescent nuclei, replication is observed in egg but not oocyte extracts. However, the oocyte extract is not inhibitory for initiation of replication, as it does not prevent replication of sperm nuclei when mixed with egg extract.
We suggest that the different capabilities of egg and oocyte extracts could provide the basis of an assay system for identifying factors involved in the initiation of DNA replication.
The role of intermediate filaments in adrenal steroidogenesis
Authors: Almahbobi Ghanim , Hall Peter F. 
Published: April 2021

ABSTRACT
Cholesterol is stored in adrenal cells as ester in lipid droplets, which are transported to mitochondria to provide a substrate for steroid hormone synthesis. Using mouse adrenal tumour cells (Y-l), we show here that approximately 33% of the adrenal cell cholesterol ester is bound tightly to intermediate filaments while the rest is either loosely attached or free in the cytosol. Specific binding of droplets to intermediate filaments was demonstrated by immunofluorescence and electron microscopy. Immunofluorescence was based upon Nile Red to stain lipid and antibodies to vimentin, actin and tubulin. Electron microscopy, including immunoelectron microscopy with protein A conjugated to gold particles (5nm), was used to examine whole mounts of cytoskeletons and intermediate filaments. Immuno fluorescence reveals that bound droplets are surrounded by a capsule containing vimentin and can be removed from the filaments by extraction with ethanol or 6 M urea. Negative staining of the urea extracts revealed isolated droplets. To the extent that cholesterol ester is the storage form of steroidogenic cholesterol, the knowledge that lipid droplets containing such esters are attached to intermediate filaments may prove important in unravelling the complex process of the transport of cholesterol to mitochondria.
The role of lamin LIII in nuclear assembly and DNA replication, in cell-free extracts ofXenopuseggs
Authors: Meier J. , Campbell K. H. S. , Ford C. C. , Stick R. , Hutchison C. J. 
Published: April 2021

ABSTRACTXenopus egg extracts, which support nuclear assembly and DNA replication, were functionally depleted of lamin Lin by inoculating them with monoclonal anti-lamin antibodies. Phase-contrast microscopy and electron-microscopy studies indicated that lamin-depleted extracts supported efficient chromatin decondensation, and assembly of double membrane structures and nuclear pores on demembranated sperm heads. Immunofluorescence microscopy suggests that lamin-antibody complexes are transported across the nuclear membrane but do not assemble into a lamina. These findings were confirmed by immunoblotting analysis of isolated nuclei. Metabolic labelling studies with either biotin-11-dUTP or [32P]dCTP, revealed that nuclei lacking a lamina were unable to initiate DNA replication and that, although such nuclei could import proteins required for DNA replication (e.g. PCNA), these proteins were apparently not organized into replicon clusters.
Modification of the pressure-probe technique permits controlled intracellular microinjection of fluorescent probes
Authors: Oparka K. J. , Murphy R. , Derrick P. M. , Prior D. A. M. , Smith J. A. C. 
Published: April 2021

ABSTRACT
The pressure probe has been widely used to study the water relations of plant cells. Here we describe a simple modification of the pressure-probe technique that permits the controlled microinjection of fluorescent probes into plant cells while simultaneously measuring cell turgor pressure. Using the pressure probe, less than 1 nl of the membrane-impermeant fluorescent dye Lucifer Yellow CH was introduced into micropipettes and subsequently injected into leaf trichome cells of Nicotiana clevelandii. Disruption of cell contents could be minimized by raising the hydrostatic pressure in the probe prior to impalement to a value approaching the anticipated cell turgor pressure. Injections to the cytosol resulted in intercellular symplastic transport of the dye in both acropetal and basipetal directions. In contrast, no symplastic transport was observed following an injection of dye into the vacuole. As measured with the pressure probe, cell turgor pressures were in the range 0.18 to 0.36 MPa; the half-time for water exchange across the cell boundary was approximately 10 s. The potential of this technique for the study of turgor-pressure-dependent intercellular transport and the hydraulic conductivities of the tonoplast, plasmalemma and plasmodesmata is discussed.
On the presence of microscopic fungi in water deleterious to Health
Authors: Lankester Edwin 
Published: April 2021

ABSTRACT
Notone of the least important services rendered by the microscope, is the facility with which the presence of organic matters, especially when living, can be detected by its agency in positions where chemical analysis fails to recognise such compounds at all. This is remarkably the case with the lower forms of animal and vegetable life which inhabit fresh, mineral, and marine waters. Some of the animals, as, for instance, the jelly-fishes, which are large enough to be seen by the naked eye, and even to present creatures of formidable dimensions, are scarcely recognisable by chemical analysis in the water in which they have existed. Such facts as these seem to indicate that the microscope may be successfully employed in investigating waters which may be suspected of containing deleterious matters, or of determining the presence of agents injurious to health. It is true that our knowledge of the forms of microscopic life which may be injurious to health is very limited, but sufficient is known to stimulate further inquiry, and to prompt further efforts to identify special organic forms with the unfitness of water for dietetical purposes. On this ground I have thought the following notes not unworthy of record.
On the Origin of Greensand, and its Formation in the Oceans of the Present Epoch
Authors: Bailey J. W. 
Published: April 2021

ABSTRACT
As an introduction to the subject of this paper, it is proper to refer to various observations which have been made of facts intimately related to those which I wish to present. That the calcareous shells of the Polythalamia are sometimes replaced by silica, appears to have been first noticed by Ehrenberg, who, in a note translated by Mr. Weaver, and published in the ‘L. E. and D. Philosophical Journal’ for 1841, vol. xviii, p. 397, says:
On the Development of the Transversely Striated Muscular Fibre, in Man, from Simple Cells
Authors: Kölliker A. 
Published: April 2021

ABSTRACT
The extensive prevalence of unicellular muscular fibres or of contractile fibre cells in the Invertebrata having been demonstratively shown, I was induced to inquire whether the mode of formation first noticed by Lebert, and afterwards by Remak, in the transversely striated muscular fibre of the frog, that, viz., acccording to which each muscular fibre is produced from a single cell, which becomes exceedingly elongated, did not apply to the case of all transversely striated fibres (‘Würz. Verb.’ viii. p. 113). I am now, in fact, enabled to show that the same mode of formation also obtains in the human subject. In a two-months embryo I found the muscles of the rudimentary foot in so undeveloped a condition, that it was by no means difficult to exhibit their very early conditions. The earliest forms seen by me were simple fusiform cells, 0·06—0·08‴ long containing in the middle portion, which was 0·001—0’015‴ in breadth, one or two elongated nuclei, and produced at either extremity into an extremely delicate filament at most 0·0004‴ in diameter, presenting at the same time no trace of transverse striation. Now from the muscular substance of the thigh and leg a complete series of forms, from these simple fibre-cells, which could be nothing else than elongated primordial embryo-cells, could be traced up to fibres 0·2—0·3‴ long and 0·002‴ wide, which were also attenuated at each end, and containing 4—9 elongated nuclei placed at considerable distances apart, and also presenting the first faint indications of a transverse striation, so that it could not be doubted that the future muscular fibres are derived simply from a growth in length and breadth of the original uninucleated fibre-cells, accompanied with an energetic multiplication of the nuclei; to Which growth is subsequently superadded a peculiar transformation of the cell-Contents. And this conclusion was the more readily arrived at from the circumstance that the nuclei of these elements presented almost all the indications of an active multiplication, which I have already described.
On some Madeiran Polyzoa
Authors: Johnson J. Yates 
Published: April 2021

ABSTRACT
We continue the account of zoophytes, brought by Mr. J. Y. Johnson from Madeira, and to which he has made some interesting additions in the present year, and kindly placed at our disposal for description. In the next number of the Journal we hope to be able to include figures of all the remaining new or imperfectly described forms brought by Mr. Johnson, and shall then give a general list of the known species derived from that most interesting locality.
The Microscope in its application to Clinical Medicine
Authors: Beale Lionel 
Published: April 2021

ABSTRACT
On the appearance of the first edition of this work (vol. ii, p. 267) we gave it our highest commendation; and the fact of its having so soon reached a second edition shows that our high estimation of its value was correct. Short, however, as has been the time since the publication of the first edition, it has been one of great advancement in the direction of microscopical research. Hasty generalizations have been corrected, incorrect observations have been exposed, increased facilities for investigation, by the improvement of the microscope, have been introduced, new methods of research have been employed, and a large addition has been made to our knowledge of minute structure, during the last four years. For many of these results we are not a little indebted to Dr. Beale’s book, and to the unwearied industry and singleness of purpose with which Dr. Beale has worked with the microscope. When we see how much work Dr. Beale has done the last four years, and recollect that during that time he has performed the duties of Physician to King’s College Hospital, and Professor of Physiology in the College, we cannot but marvel at the extent of his labours, and hope that he is not taxing his physical powers to an extent which he or his friends may have occasion to lament.
The Aquarian Naturalist ; a Manual for the Sea-side
Authors: Jones Thomas Rymer 
Published: April 2021

ABSTRACT
Having been indebted to the politeness of the publisher for a copy of this elegant drawing-room volume, we have pleasure in directing the attention of those for whose benefit it is intended to its numerous attractions, though unable to perceive that the Author has made much use of the microscope in any researches which can be regarded as novel in it.
Manual of Technical Analysis, a guide for the testing and valuation of the various natural and artificial substances employed in the Arts and Domestic Economy, founded upon the ‘Handbuch’ of Dr. P. A. Bolley
Authors: Paul Benjamin 
Published: April 2021

ABSTRACT
In the examination of the structure and composition of the various natural substances used by man in the Arts and Domestic Economy, it is frequently necessary to use more than one instrument of investigation. Where chemical analysis fails the microscope succeeds, and where the microscope is valueless the chemical reagents will frequently establish facts of the first importance. It not uncommonly happens that these two means of investigation are necessary to arrive at correct conclusions. Substances which cannot be obtained in sufficient quantities to be analysed with the naked eye may be chemically manipulated with the greatest success under the microscope. It is on this ground that the microscope and chemical experiment frequently meet, and the investigator of nature and the man of business must appeal to both.
Descriptions of New Species Of British Diatomaceæ, Chiefly observed by the late Professor Gregory
Authors: Greville Robert Kaye 
Published: April 2021

ABSTRACT
Towards the close of the year 1857, my lamented friend, the late Professor Gregory, was engaged in the examination of some Diatomaceous gatherings, the results of various dredgings made by Professor Balfour in Lamlash Bay. He had. detected a considerable number of forms which he believed to be undescribed ; and with reference to their publication I had completed drawings of a portion of the series, when he was attacked by his last illness. It does not appear that he had reduced any of his observations on these new species to writing ; at least, I have not been able to find a single memorandum on the subject. So that, however desirous I may be to secure to the name of my late friend the credit due to his discoveries, I fear that, even with the aid of his collection, which has been most kindly presented to me by his widow, I shall perform this duty very imperfectly. It unfortunately happens that, in some cases, the slides which contained the objects to be drawn were returned to him for description, and I have neither been able to find the original slides (in the absence of any distinctive mark or label), nor additional examples of the forms in question. The present communication consequently does not contain a notice even of all the species of which I had made drawings. The wonderful memory possessed by Professor Gregory rendered him independent of temporary notes. The careful study he bestowed upon the forms which came under his eye, fixed every character, however minute, in his mind, and it was not until he had completed his investigations that he sat down to record them. By his death Science has lost a most successful explorer, as well as one of the most patient and indefatigable of microscopic observers.
On the Calcareous Corpuscles of the Trematoda; and on the Genus Tetracotyle
Authors: Claparède E. 
Published: April 2021

ABSTRACT
The calcareous corpuscles of different entozoa have frequently attracted the attention of observers. For a long time regarded as ova, their calcareous constitution was at length recognized, and at present they are universally looked upon as an earthy deposit in the integument. Siebold, for instance, compares them with the calcareous bodies found in the integument of the Holuthuriæ and in the soft parts of many polypes. I have, however, for some time, been aware that these corpuscles, in some Trematoda at any rate, have a certain relation to the excretory apparatus. This observation was first made in April, 1855, in Diplostomum rachiæum, Henle, from the spinal canal Of the Frog. In this instance, it was obvious at first sight that a minute vessel proceeded from each corpuscle. Closer examination showed that each corpuscle is contained in a capsule fitting pretty closely around it, and whose wall is continuous with that of the tubule. Several of these vessels unite into a single branch, which communicates again with one of the ramifications of the excretory system. This system in D. rachiæum is constituted of a slender, gradually enlarging trunk, which runs from behind forwards in the middle line of the body, and is connected, at the anterior extremity of the animal, by a branch on either side, with the lateral trunks. The latter descend nearly parallel with the border and, gradually enlarging, open at the hinder end into the two-pointed contractile vesicle. From each of these three main trunks numerous vibratile vessels are given off; and besides these they are connected with each other by numerous transverse branches; one of which, in particular, may always be remarked passing across immediately in front of the abdominal acetabulum. As is well known, Leydig * has regarded this excretory system as a ramified intestine, considering, on the other hand, the true intestine as a bifurcate excretory apparatus.
On some of the Rarer or Undescribed Species of Diato-Maceæ. Part I
Authors: Brightwell T. 
Published: April 2021

ABSTRACT
It is my purpose to give in this and some following papers descriptions of some of the many undescribed or unfigured species of Diatomaceæ, chiefly marine, which still are found in our cabinets; illustrated by Mr. Tuffen West’s excellent figures, they will, I trust, be acceptable and useful to algologists.
Das Mikroskop; Theorie, Gebrauch, Geschichte, und gegen-wärtige Zustand desselben. [the Microscope; its theory, use, history, and present state.]
Authors: Harting P. 
Published: April 2021

ABSTRACT
Professor Harting’s work on the ‘Microscope,’ originally written in the Dutch language, and consequently a sealed book to all but a very few, appeared in three distinct portions or volumes, to which a voluminous appendix was added last year. The whole was thus brought up to the present time.