bluuebunny/crossref_metadata_2025_split huggingface dataset:
The neuron types of the glomerular layer of the olfactory bulb
Authors: Pinching A. J. , Powell T. P. S. 
Published: April 2021

ABSTRACT
The neurons of the glomerular layer of the rat olfactory bulb have been studied using Nissl staining and Golgi-Kopsch impregnation in light microscopy to define the size, shape and morphological features of individual cell somata, dendrites and axons; these have been correlated with electron-microscopic material in which fine-structural characteristics were also noted for each cell type, particularly synaptic specializations. Three neuron types are described: the external tufted and periglomerular cells of classical microscopy, and additional, superficial short-axon cells; a description of the glomerular arborizations of the mitral and deep tufted cells is also included. The tufted and mitral cells show large, non-spiny glomerular dendritic arborizations, having terminal varicosities, the external tufted cells being more limited in their branching than the deeper cells. External tufted cells have large somata and abundant cytoplasm containing stacks of Nissl material; their main dendrites are characterized by pale cytoplasm and a regular array of neurotubules. Reciprocal dendro-dendritic and somato-dendritic synapses are commonly found, the tufted/mitral cells containing spherical vesicles and contacting by means of asymmetrical membrane thickenings; the other profile involved is a gemmule containing large flattened vesicles and associated with a symmetrical thickening. The periglomerular cells are smaller, with a spiny glomerular arborization, as well as some other dendrites; all the dendrites of these cells tend to be of irregular outline. They have a dark nucleus and very little somatic cytoplasm; somatic and dendritic appendages are common and often contain large flattened vesicles. Synapses oriented from the dendritic shaft or gemmule also show such vesicles, invariably associated with symmetrical thickenings. The superficial short-axon cells are characterized by the entirely periglomerular distribution of their dendrites, which are varicose and rarely branch. Of intermediate soma dimensions, but containing dispersed Nissl material, these cells and their stem dendrites show no regions that can be designated as presynaptic.
Features of axon initial segments, axo-somatic and axo-dendritic synapses are also described for each cell, as well as some unusual glial relationships. Reasons are adduced for relating the superficial short-axon cell to the axon terminal type containing small flattened vesicles, as well as for considering that the external tufted and periglomerular cells show the same synaptic specializations at their axon terminals as at their dendritic and somatic synapses. The cells of the glomerular layer are compared with those of the deeper layers of the bulb and atypical synaptic specializations discussed; some physiological implications of these findings are considered.
The neuropil of the periglomerular region of the olfactory bulb
Authors: Pinching A. J. , Powell T. P. S. 
Published: April 2021

ABSTRACT
The periglomerular region of the olfactory bulb, apart from containing the somata and stem dendrites of the cells contributing to the glomeruli, is the sole region of distribution of the periglomerular cell thin dendrites and the short-axon cell dendrites. It is also the major site of termination of all axons to the glomerular layer except the olfactory axons — i.e. tufted cell collaterals, periglomerular cell and short-axon cell axons and centrifugal fibres. Its characteristic neuropil has been studied with the electron microscope to define the cells of origin of the types of neuronal process and their synaptic relationships. Three types of axon terminals have been found: those with spherical, large flattened and small flattened vesicles, which are deduced to derive from tufted cell collaterals or centrifugal fibres, periglomerular cell and short axon-cell axons respectively; those with spherical vesicles are consistently associated with asymmetrical membrane thickenings and those with either type of flattened vesicles with symmetrical thickenings. The thin periglomerular cell dendrites are very irregular and often have a somewhat dense cytoplasm, rich in ribosomes; they may become extended into very attenuated glia-like sheets that surround the mitral or tufted cell stem dendrites, from which they may receive synaptic contacts. Such dendrites also receive some synapses from all 3 types of axon in the periglomerular region. The short-axon cell dendrites are thick and varicose and show no sign of synaptic specialization oriented from them; they have few spines but receive many asymmetrical-type synapses on their shafts. Both axon terminal types synapsing with symmetrical thickenings are also found on the shafts. The evidence obtained from the study of normal material is summarized and the various cellular roles considered. In the light of observations on the olfactory bulb, it is suggested that dendrites may be divided into 2 major classes: those that only receive synapses (Class A) and those that make synaptic contacts as well as receiving them (Class B). Further comparisons with the deep layers of the bulb and physiological implications are discussed.
Cell migration in wool follicles of sheep
Authors: Chapman R. E. 
Published: April 2021

ABSTRACT
The migration of cells in wool follicles was studied by autoradiography of skin biopsies taken at half-day intervals from 2 to 5 days after intradermal injections of tritiated thymidine in 8 Corriedale sheep on different planes of nutrition. Cell migration rates were not the same in all follicles. Therefore, the shortest and longest times for cells to migrate to defined levels in the follicles were determined. Cells of the inner root sheath moved up the proximal part of some follicles ahead of contemporaneously formed cells in the fibre. Subsequently, cells in the fibre reached the level where the fibre attained its definitive form in about 2·5–4 days. Cell migration also occurred in the outer root sheath, and sloughing of both outer and inner root sheath cells was observed. In the distal half of the follicles, cells of the root sheaths and of the fibre migrated at similar rates, which suggested that the inner root sheath and fibre were carried through the upper part of the follicle by migrating cells of the outer root sheath.
Cell migration times were about 0·5 day less in fat sheep on large and moderate food intakes than in lean sheep on restricted intakes.
Effects of synthetic polycations on leucine incorporation, lactate dehydrogenase release, and morphology of human umbilical vein endothelial cells
Authors: Morgan David M. L. , Clover Julie , Pearson Jeremy D. 
Published: April 2021

ABSTRACT
Naturally occurring cationic proteins secreted by human granulocytes have pro-inflammatory effects including induction of increased vascular permeability and oedema, which are likely to be mediated by damage to vascular endothelium. Synthetic cationic polyamino acids have been shown to exert similar inflammatory effects in vivo. We have therefore used a range of synthetic polycationic amino acids to investigate the characteristics required to cause endothelial cell damage, assessed by in vitro inhibition of leucine incorporation into macromolecules by human umbilical vein endothelial cells (HUVEC) in culture. Exposure of HUVEC to 20 nM–2 μM cationic polypeptides of similar Mr(av) (≈40000) in the presence of 20% serum produced a dose-dependent inhibition of [3H] leucine incorporation by polymers of ornithine, arginine or lysine. Similar results were obtained using [3H]thymidine. Neutral or anionic polypeptides of similar Mr were without effect. The molar potency of polylysines increased over the range Mr 40000–120000, while polylysines of Mr(av; &lt;25 000 had no effect. In the absence of serum, inhibition occurred more rapidly and at lower doses. Inhibition of leucine and thymidine incorporation was time-dependent, e.g. exposure to 800 nM-polylysine, Mr (av) 90 000, led to progressively increasing inhibition that was complete after 24 h exposure, and was irreversible. The effects of polycations could not be blocked by pretreatment of the cells with polyanions. Precoating of the culture surface with polylysines had no effect on leucine incorporation by HUVEC or their subsequent response to polylysines in solution. Exposure to the peptide Arg-Gly-Asp-Ser inhibited incorporation by 30% but did not increase susceptibility to polylysine. The extent of inhibition of radiolabel incorporation was correlated with changes in cell morphology and release of a cytoplasmic enzyme (1actate dehydrogenase). We conclude that cationic proteins can exert significant, essentially irreversible, cytotoxic effects on endothelium, the magnitude of which depends on the density of cationic residues interacting with the cell and the time of exposure to the polycation. The use of synthetic amino acid polymers in such a model system provides a means of investigating the characteristics of cationic polypeptides that affect endothelial cells and the nature of the responses induced.
Immunochemical and immunocytochemical identification of a myosin heavy chain polypeptide in Nicotiana pollen tubes
Authors: Tang Xlaojing , Hepler Peter K. , Scordilis Stylianos P. 
Published: April 2021

ABSTRACT
A myosin heavy chain polypeptide has been identified and localized in Nicotiana pollen tubes using monoclonal anti-myosin antibodies. The epitopes of these antibodies were found to reside on the myosin heavy chain head and rod portion and were, therefore, designated anti-S-1 (myosin S-l) and anti-LMM (light meromyosin). On Western blots of the total soluble pollen tube proteins, both anti-S-1 and anti-LMM label a polypeptide of approximately 175 000Mr. Immunofluorescence microscopy shows that both antibodies yield numerous fluorescent spots throughout the whole length of the tube, often with an enrichment in the tube tip. These fluorescent spots are thought to represent vesicles and/or organelles in the pollen tubes. In addition to this common pattern, anti-S-1 stains both the generative cell and the vegetative nuclear envelope. The different staining patterns of the nucleus between anti-S-1 and anti-LMM may be caused by some organization and/or anchorage state of the myosin molecules on the nuclear surface that differs from those on the vesicles and/or organelles.
Activation of the hprt gene on the inactive X chromosome in transformed diploid female Chinese hamster cells
Authors: Grant Stephen G. , Worton Ronald G. 
Published: April 2021

ABSTRACT
Treatment with 5-azacytidine, a potent inhibitor of DNA methylation, was used to induce activation of the selectable hprt gene on the inactive X chromosome in a diploid female Chinese hamster cell line. The transformed, stably diploid cell line F3B was selected in media containing the lethal purine analogue 6-thioguanine, to generate a phenotypically HPRT− mutant, F3BT1, of presumed genotype hprt − /hprt-+), where (+) represents the presumably wild-type allele on the inactive X chromosome. Treatment of F3BT1 with 5-azacytidine resulted in phenotypic reversion to HPRT + at a frequency greater than 10−3. Similar treatment of 6-thioguanine-resistant control lines derived from male cells, or from CHO (which has no inactive X chromosome), had no effect on the frequency of phenotypic reversion, indicating that activation of the hprt-+) allele, rather than reversion of the hprt− is responsible. This conclusion is substantiated by documentation of the low mutagenic capacity of 5-azacytidine in this system. Proof that the hprt-+) allele can be activated by 5-azacytidine treatment was obtained in somatic cell hybrids in which hprt gene products from the active and inactive X chromosomes could be distinguished by isoelectric focusing. Our results demonstrate that X-linked gene activation associated with generalized DNA demethylation occurs with high frequency in transformed diploid Chinese hamster cells.
Anionic site behavior in Leishmania and its role in the parasite—macrophage interaction
Authors: Saraiva E. M. B. , Vannier-Santos M. A. , Silva-Filho F. C. , Souza W. De 
Published: April 2021

ABSTRACT
The behavior of cationized ferritin (CF) binding sites on the surface of Leishmania mexicana amazonensis (amastigotes, infective and non-infective promastigotes) and their participation in the interaction with macrophages were evaluated. Glutaraldehyde-fixed parasites treated with CF present a uniform labelling over the whole cell surface. However, living parasites displayed CF patches and caps. Capping was usually seen towards the anterior (flagellated) portion of the cells, where shedding phenomena took place. These processes were inhibited by sodium azide but not by low temperature (4°C). CF treatment of non-infective promastigotes led to an increase in their uptake by macrophages, whereas the uptake of amastigotes or infective promastigotes was not significantly altered. The effect of CF on the parasite surface charge was analyzed by whole-cell microelectrophoresis. The mean electrophoretic mobility (EPM) of non-infective promastigotes was decreased by 26%, while once again the other parasite forms were not significantly affected. Transmission electron microscopy of mouse peritoneal macrophage cultures, fixed after interaction with CF-labelled parasites, revealed that both amastigotes and infective promastigotes quickly removed bound CF. Therefore CF was seen neither in parasite-macrophage attachment areas nor in parasitophorous vacuoles. On the contrary, non-infective promastigote-macrophage attachment areas were remarkably large and preferentially comprised CF-labelled membranes. These results strongly suggest an important participation of cell surface anionic sites in the L. mexicana amazonensis-macrophage interaction.
The effect of antisense RNA to fibronectin on the malignancy of hybrids between melanoma cells and normal fibroblasts
Authors: Steel Diana M. , Harris Henry 
Published: April 2021

ABSTRACT
An expression vector containing a cDNA complementary to 1·3 kb of the 5’ coding sequences of the fibronectin gene in the antisense orientation with respect to its promoter was introduced by electroporation into hybrids between melanoma cells and normal fibroblasts in which malignancy was suppressed. Immunofluorescence analysis of clones transfected with the antisense cDNA showed a dramatic decrease in the amount of fibronectin on the cell surface compared to that seen on the surface of the untransfected hybrid cells or of cells transfected with fibronectin cDNA in the sense orientation or with the expression vector alone. Four out of five clones transfected with the antisense cDNA were highly tumorigenic, whereas transfectants containing either the sense fibronectin construct or the expression vector alone remained non-tumori-genic. These results suggest that antisense RNA to fibronectin may be able to abrogate the suppression of malignancy imposed on the hybrid cells by the fibroblast parent.
Fine–structural aspects of bromodeoxyuridine incorporation in sister chromatid differentiation and replication banding
Authors: Jack Elspeth M. , Harrison Christine J. , White Gavin R. M. , Ockey Charles H. , Allen Terence D. 
Published: April 2021

ABSTRACT
The structure of harlequin-stained chromosomes following substitution with low levels of 5-bromodeoxyuridine (BrdUrd) over two cell cycles and high levels over the last part of one cycle (replication banding) was studied in Chinese hamster ovary (CHO) cells. By using correlative light (LM) and scanning electron microscopy (SEM), it was shown that the effects of both the ultraviolet light (u.v.) and hot SSC treatment steps of the harlequin staining procedure were necessary to obtain sister-chromatid differentiation (SCD) or replication banding, u.v. treatment alone resulted in dark Giemsa staining of both chromatids with SEM morphology of short compact protuberances and an overall flattened smooth appearance in both the unsubstituted and BrdUrd-substituted chromatids, a morphology essentially similar to that of untreated chromosomes. SSC alone on the other hand resulted in dark-staining chromatids with an SEM morphology of raised, 100sely packed 100ps of fibres in both types of chromatids, u.v. and SSC treatment together resulted in dtfferentiation, with dark-staining unifilarly (TB) chromatids in the LM corresponding to raised 100sely packed 100ps in the SEM and pale bifilarly (BB) chromatids corresponding to the smooth compact flattened SEM appearance. Where the BrdUrd-substituted strand became the template (BT), or when the nascent strand TB contained high levels of BrdUrd substitution in replication banding, the chromatid stained pale and showed the compact smooth appearance in the SEM. The Giemsa staining ability and ultra- structural morphology of harlequin staining is discussed with respect to putative DNA loss and also in terms of preferential protein–protein, protein–DNA cross-linkage in BrdUrd-containing DNA. These changes are also compared with the ultrastructural morphology observed after other banding methods, where deterioration of protein and DNA-protein interaction resulting in aggregation of chromatin fibres appears to be the major mechanism.
Myosin associated with the surfaces of organelles, vegetative nuclei and generative cells in angiosperm pollen grains and tubes
Authors: Heslop-harrison J. , Heslop-harrison Y. 
Published: April 2021

ABSTRACT
Myosin, detected by immunofluorescence using an antibody to bovine skeletal and smooth muscle myosin, has been localised on individual identifiable organelles from the grasses Alopecurus praten-sis and Secale cereale, and on the surfaces of vegetative nuclei and generative cells from pollen and pollen tubes of Hyacinthus orientalis and Hel-leborus foetidus. Taken in conjunction with recent evidence showing that the growing pollen tube contains an actin cytoskeleton consisting of numerous mainly longitudinally oriented microfilament bundles, and that isolated pollen-tube organelles show ATP-dependent movement along the actin bundles of the giant cells of the characeous algae, this finding suggests that an actomyosin motility system is present in pollen tubes, and indicates that the movements of the different classes of inclusions are driven by interaction of the surface myosin with the actin fibrils at the zones of contact.
Keratin expression in human mammary epithelial cells cultured from normal and malignant tissue: relation to in vivo phenotypes and influence of medium
Authors: Taylor-Papadimitriou J. , Stampfer M. , Barter J. , Lewis A. , Boshell M. , Lane E. B. , Leigh I. M. 
Published: April 2021

ABSTRACT
The luminal and basal epithelial cells in the human mammary gland can be distinguished in tissue sections on the basis of the pattern of keratins they express. Moreover, the invasive cells in primary carcinomas show a keratin profile that corresponds to that of the dominant luminal cell (7, 8, 18, 19). When homogeneous populations of luminal epithelial cells from milk or from breast cancer metastases are cultured the profile of keratin expression seen in vivo is maintained. We have therefore used monospecific antibodies reactive with individual keratins to examine the phenotype of cells cultured in three different media from reduction mammoplasty tissue that contains both luminal and basal cells. The phenotype of cells cultured from primary breast cancers in one of these media (MCDB 170) has also been examined. In characterizing cell phenotypes, antibodies to a polymorphic epithelial mucin (PEM) expressed in vivo by luminal cells, and to smooth muscle (a) actin, expressed in vivo by basal cells, have also been used. Our results show that proliferation of different cell phenotypes is selected for in different media. In milk mix (MX) developed for growth of luminal cells from milk, only the luminal cell phenotype proliferates (for only 1 or 2 passages). In medium MCDB 170, which was developed for long-term growth of human mammary epithelial cells from reduction mammoplasty organoids, cells from the basal layer proliferate, while in MM medium the basal phenotype dominates, but a few cells with the luminal phenotype are found. Around passage 3, in medium MCDB 170, most cells senesce and a subpopulation of cells proliferates on further passage. These cells retain expression of the basal epithelial keratins but also express some features characteristic of luminal epithelial cells, suggesting that the basal layer may contain a stem cell that can develop along the luminal lineage. In culture, however, they do not express keratin 19, which in vivo is a feature of the fully differentiated luminal cell. The cells cultured from primary breast cancer in medium MCDB 170 have a similar keratin profile to that of the normal cells cultured in this medium. They do not express keratin 19, even though the invasive cells in primary cancers homogeneously express this keratin in vivo. The invasive phenotype, which in its keratin profile corresponds to the differentiated luminal cell and that of the metastatic cancer lines, cannot be cultured from primary breast cancers using MX, which supports proliferation of the corresponding normal cell.
Proliferative behaviour of fibroblasts in plasma-rich culture medium
Authors: Umeno Yoshikazu , Okuda Atsuyuki , Kimura Genki 
Published: April 2021

ABSTRACT
We examined the proliferative behaviour in tertiary culture cells of human skin fibroblasts (HSF) as well as cells of the rat 3Y1 diploid fibroblast line placed on a plastic substratum in a nutrient-rich medium containing high concentrations of platelet-poor plasma (PPP). Autochthonous human PPP was used for the HSF cells and heat-treated (at 56 °C for 30 min) bovine PPP was used for the 3Y1 cells. In both types of cells, the saturation cell density rose with increasing PPP concentration and reached a plateau at 30–90% PPP. When the cells were cultivated in serum, the saturation densities were the same as those with the same concentrations of corresponding PPP in both the HSF and 3Y1 cells. When the cells were arrested at a saturation cell density in a medium containing 10% PPP and then were refed with a fresh medium containing 90% PPP, DNA synthesis and cell division occurred in both types of fibroblasts. This effect was either reduced in the HSF cells or enhanced in the 3Y1 cells by the addition of platelet lysate. TGF-β1 added to the fresh medium containing 90% PPP also inhibited the induction of DNA synthesis in the HSF cells but not in the 3Y1 cells. The inhibitory effect of the platelet lysate was neutralized by anti-TGF-β1 IgG. On the other hand, PDGF added to the fresh medium had no effect on either type of cells. These results suggest that cultured fibroblasts are capable of proliferating on a plastic substratum under fluid conditions that essentially reflect the fluid environment of the body, as long as sufficient nutrients are supplied. Platelet lysate represses the proliferation of HSF cells, possibly through the inhibitory effect of TGF-β1, and promotes the proliferation of 3Y1 cells by growth factor(s) other than PDGF and TGF-β1.
The first transition point of the mutant cdc2.33 in the fission yeast Schizosaccharomyces pombe
Authors: Novak B. , Mitchison J. M. 
Published: April 2021

ABSTRACT
We show that the first of the two transition points of cdc2.33, a mutant of Schizosaccharomyces pombe, exists in exponential phase cells. Using flow cytometry and a double-block experiment, we have measured the position of this transition point both in the single mutant and in the double mutant cdc2.33 wee 1.6. In the single mutant, this point is in early G1 In the double mutant, however, this point is only delayed slightly, if at all, despite much larger delays in the S period and in the transition point of cdc10, another‘start’ mutant. There istherefore a significant dissociation in the timing of what are thought to be two start events, and the first one appears not to be subject to a size controf and to be associated with the completion of mitosis rather than the G1/S boundary.