bluuebunny/crossref_metadata_2025_split huggingface dataset:
Transformation of a polygonal cellular pattern during sexual maturation of the avian oviduct epithelium: computer simulation
Authors: Honda Hisao , Yamanaka Hachiro , Eguchi Goro 
Published: April 2021

ABSTRACT
A peculiar cellular pattern resembling a checkerboard has been observed on the luminal surface of the oviduct epithelium of an adult Japanese quail. The epithelium is a monolayer cell sheet and consists of two types of columnar cells, ciliated cells (C-cells) and gland cells (G-cells) assembled in alternating blocks. The pattern develops, during sexual maturation, from a kagome-like pattern (in which large C-cells are surrounded by small G-cells) characteristic of the immature oviduct. In the present paper, computer simulations of the pattern transformation from kagome to checkerboard were performed assuming a few properties of individual cells.
The adult checkerboard-like pattern is not strictly rectangular, but is deformed toward a honeycomb pattern. In theoretical considerations the assumption that adhesion is stronger between unlike cells than between like cells formed an ideal checkerboard pattern, because all cell boundaries in it are edges along which unlike cells meet. On the other hand, a honeycomb pattern formed after assuming that the boundary length of the cellular pattern is minimized (caused by contraction of bundles of microfilaments running along lateral boundaries of the columnar epithelial cell while keeping contact between neighbouring cells). The actual checkerboard-like pattern was considered to be in a balanced state between the effects of (1) the strong adhesion between unlike cells, and (2) the boundary contraction. Using a computational analysis, this consideration enabled us to obtain a quantitative parameter value for the difference between cell adhesions of unlike cells and of like cells.
C-cells divided once during the kagome-checkerboard transformation, while G-cells did not divide. We performed computer simulations starting with the kagome pattern in which all C-cells divided once. The computer program of the boundary shortening procedure we used involved the quantitative parameter value for differential cell adhesion obtained as described above. A checkerboard pattern was successfully generated in the simulation. It is concluded that the strong adhesion between unlike cells and the boundary shortening have important roles in formation and maintenance of the kagome and checkerboard patterns of the avian oviduct epithelium.
Chromosome analysis of single-pronuclear haploid parthenogenetic blastocysts and their inner cell mass derivatives
Authors: Schnebelen M. T. , Kaufman M. H. 
Published: April 2021

ABSTRACTSingle-pronuclear haploid parthenogenetically activated mouse embryos were transferred to the oviducts of suitable recipients. One group of embryos was isolated at the morula stage and subsequently allowed to develop to the expanded blastocyst stage in vitro. Intact embryos were either analysed by the air-drying technique at that stage to determine their total cell number and ploidy, or treated by immunosurgery to isolate their inner cell mass. These were either analysed to establish their total cell number and ploidy, or retained in culture for an additional 24 h or 72 h. The inner cell mass derivatives were then analysed to establish the total cell number and ploidy. A second group of recipients was ovariectomized on the 4th day of pseudopregnancy, treated with Depo-Provera and blastocysts recovered 5 or 6 days later. The ‘delayed’ blastocysts recovered were treated by immunosurgery, and the inner cell masses isolated and either analysed at this time or transferred to culture for 72 h, 96 h or 144h. As in the previous groups, the inner cell mass derivatives were analysed to establish the total cell population present and their ploidy. The analysis of this material was found to be technically particularly difficult, though in general the non-‘delayed’ embryos and their inner cell mass derivatives yielded higher success rates than the ‘delayed’ inner cell mass derivatives. The .‘delayed’ inner cell masses initially contained on average about twice the number of cells compared to the number present in those isolated from the non-‘delayed’ expanded blastocysts. Cellular profiferation occurred in all the groups retained in culture, though only a small proportion of the cells analysed gave ‘scorable’ mitotic cells in which the ploidy could be unequivocally determined. In general, in both the non-‘delayed’ and ‘delayed’ groups, the proportion of diploid mitotic cells observed increased with their duration in culture, though this effect was clearly more marked in the ‘delayed’ series. The present study indicated that the chance of obtaining haploid mouse cell lines in the future might be increased by using inner cell masses derived from non-‘delayed’ rather than ‘delayed’ blastocysts despite their initial reduced cell number at the time of explantation into tissue culture..
The relationship between emerging neural crest cells and basement membranes in the trunk of the mouse embryo: a TEM and immunocytochemical study
Authors: Sternberg J. , Kimber S. J. 
Published: April 2021

ABSTRACTThe earliest stage of neural crest cell (NCC) migration is characterized by an epitheliomesenchymal transformation, as the cells leave the neural tube. There is evidence that in a number of cell systems this transformation is accompanied by alteration or depletion of associated basement membranes. This study examines the ultrastructural relationship between mouse NCCs and adjacent basement membranes during the earliest stages of migration from the neural tube. Basement membranes were identified by transmission electron microscopy (TEM) and immunofluorescence using antibodies to type-IV collagen. The ultrastructural features of NCCs and their relationship with surrounding tissues were also examined using TEM. In the dorsal region of the neural tube, from which NCCs originate, the basement membrane was depleted or absent, and with the immunofluorescence technique it was shown that this pattern was reflected in a deficit of type-IV collagen. TEM observations indicated that ultrastructurally NCCs differ from their neuroepithelial neighbours only in overall cell shape and their relationship to other cells and the extracellular matrix.
Gonadal development of the chick embryo following microsurgically caused agenesis of the mesonephros and using interspecific quail—chick chimaeras
Authors: Rodemer Eva S. , Ihmer Alice , Wartenberg H. 
Published: April 2021

ABSTRACT
Mesonephric agenesis was achieved by microsurgical excision of the left Wolffian duct and the underlying intermediate mesoderm of different regions between somites 16 and 23 in chickens after 50–52 h of incubation (stage 14 HH). Quail-chick chimaeras were produced by transplantation of corresponding quail tissue in the region of somites 18–21.
A morphometrical analysis of the mesonephric and gonadal area in cross sections shows that the intermediate mesoderm from somites 16 to 23 develops into the mesonephros. A partial agenesis of the mesonephros brought about by removal of the intermediate mesoderm at the level of somites 18 to 21 at stage 14 leads to a mean reduction of the gonadal volume of 37·8 % compared to the volume of the untreated side at stage 30. Transplantation of quail intermediate mesoderm in this region of the excision results in development of a hybrid mesonephros. Consequently, the gonads are invaded and colonized by quail cells mobilized from mesonephric corpuscles examined at stage 30, 35 and 36.
These results are discussed in terms of the origin of the gonadal stroma during this developmental period; they show that in the region from the third to the sixth segment the ventromedial part of the differentiating mesonephros participates in the contribution of stromal cells to the gonad.
Axon guidance in the insect periphery
Authors: Palka John 
Published: April 2021

ABSTRACTThe central theme of this essay is the importance of considering neural development, including axonal pathfinding, as but one of a multitude of simultaneously occurring developmental processes. It is very tempting to suppose that the observed regularity of axonal outgrowth is the consequence of mechanisms dedicated to axon guidance, for example, that specific paths are laid down whose exclusive function is to guide axons. I propose to argue from two case studies in insects that regularity does not imply such exclusiveness.
Genes that control dorsoventral polarity affect gene expression along the anteroposterior axis of theDrosophilaembryo
Authors: Carroll Sean B. , Winslow Gary M. , Twombly Vern J. , Scott Matthew P. 
Published: April 2021

ABSTRACTAt least 13 genes control the establishment of dorsoventral polarity in the Drosophila embryo and more than 30 genes control the anteroposterior pattern of body segments. Each group of genes is thought to control pattern formation along one body axis, independently of the other group. We have used the expression of the fushi tarazu {ftz) segmentation gene as a positional marker to investigate the relationship between the dorsoventral and anteroposterior axes. The ftz gene is normally expressed in seven transverse stripes. Changes in the striped pattern in embryos mutant for other genes (or progeny of females homozygous for maternal-effect mutations) can reveal alterations of cell fate resulting from such mutations. We show that in the absence of any of ten maternal-effect dorsoventral polarity gene functions, the characteristic stripes of ftz protein are altered. Normally there is a difference between ftz stripe spacing on the dorsal and ventral sides of the embryo; in dorsalized mutant embryos the ftz stripes appear to be altered so that dorsal-type spacing occurs on all sides of the embryo. These results indicate that cells respond to dorsoventral positional information in establishing early patterns of gene expression along the anteroposterior axis and that there may be more significant interactions between the different axes of positional information than previously determined.
Lithium inhibits morphogenesis of the nervous system but not neuronal differentiation in Xenopus laevis
Authors: Breckenridge Lorna J. , Warren R. L. , Warner Anne E. 
Published: April 2021

ABSTRACT
Xenopus embryos treated with 100 mM-lithium from the 2-to 4-cell stage to the early blastula stage (4h) failed to neurulate and developed without a discernible anteroposterior axis. The internal structure of defective embryos was grossly disorganized, but immunohistochemical staining with cell-type-specific antibodies revealed differentiated nerve and muscle cells. Quantitative assay in tissue cultures from control and acutely abnormal lithium-treated embryos showed that neural differentiation was enhanced and muscle differentiation unaffected. The embryos took up about 0·5 mM-lithium at threshold, maximal effects resulted at 2-3 mM. Most of the lithium was extruded from the cells into the blastocoel fluid, where lithium reached 17 mM. The threshold intracellular concentration was about 150 μM. Lithium uptake rose steeply as the osmotic/ionic strength of the bathing medium increased. Sodium, potassium and lithium were equally able to increase the permeability of the embryo. However, sodium ions enhanced, while potassium ions interfered with, the uptake of lithium. Treatment with lithium at progressively later stages reduced the developmental defects and neural differentiation returned to normal levels. The uptake of lithium did not decline concomitantly. We conclude that lithium does not inhibit neural induction, but interferes with dorsal patterning. The sensitivity of the embryo to lithium is determined by developmental stage. The very low, effective intracellular concentrations may be important in understanding the mechanism of lithium-generated defects.
Complicated colobomatous microphthalmia in the microphthalmic(mi/mi)mouse
Authors: Scholtz C. L. , Chan K. K. 
Published: April 2021

AbstractA study of the development of the eye in the cinnamon mouse, homozygous for the gene for microphthalmia (mi), has shown that the microphthalmia is due to failure of secondary vitreous formation associated with a coloboma. The retina is dystrophic but there is a residual population of large ganglion cells and the optic nerve also contains ganglion cells. All these ganglion cells have cytoplasm similar to the retinal ganglion cells in the normal controls. It is postulated that they communicate with axons in the optic nerve. In addition, the outer epithelial layer of the eye cup, which normally becomes pigmented, forms retinal tissue in the homozygous mouse and this is also true of the dorsal part of the eyestalk near the eye.
Rescue of the mutant phenotype by reexpression of full-length vinculin in null F9 cells; effects on cell locomotion by domain deleted vinculin
Authors: Xu Weiming , Coll Jean-Luc , Adamson Eileen D. 
Published: April 2021

ABSTRACT
Vinculin plays a role in signaling between integrins and the actin cytoskeleton. We reported earlier that F9-derived cells lacking vinculin are less spread, less adhesive, and move two times faster than wild-type F9 cells. Expression of intact vinculin in null cells restored all wild-type characteristics. In contrast, expression of the head (90 kDa) fragment exaggerated mutant characteristics, especially locomotion, which was double that of vinculin null cells. Expression of the tail domain also had a marked effect on locomotion in the opposite direction, reducing it to very low levels. The expression of the head plus tail domains together (no covalent attachment) effected a partial rescue towards wild-type phenotype, thus indicating that reexpressed polypeptides may be in their correct location and are interacting normally. Therefore, we conclude that: (1) the head domain is part of the locomotory force of the cell, modulated by the tail, and driven by the integrin/matrix connection; (2) intact vinculin is required for normal regulation of cell behavior, suggesting that vinculin head-tail interactions control cell adhesion, spreading, lamellipodia formation and locomotion.
The sparing of extraocular muscle in dystrophinopathy is lost in mice lacking utrophin and dystrophin
Authors: Porter J. D. , Rafael J. A. , Ragusa R. J. , Brueckner J. K. , Trickett J. I. , Davies K. E. 
Published: April 2021

ABSTRACT
The extraocular muscles are one of few skeletal muscles that are structurally and functionally intact in Duchenne muscular dystrophy. Little is known about the mechanisms responsible for differential sparing or targeting of muscle groups in neuromuscular disease. One hypothesis is that constitutive or adaptive properties of the unique extraocular muscle phenotype may underlie their protection in dystrophinopathy. We assessed the status of extraocular muscles in the mdx mouse model of muscular dystrophy. Mice showed mild pathology in accessory extraocular muscles, but no signs of pathology were evident in the principal extraocular muscles at any age. By immunoblotting, the extraocular muscles of mdx mice exhibited increased levels of a dystrophin analog, dystrophin-related protein or utrophin. These data suggest, but do not provide mechanistic evidence, that utrophin mediates eye muscle protection. To examine a potential causal relationship, knockout mouse models were used to determine whether eye muscle sparing could be reversed.
Mice lacking expression of utrophin alone, like the dystrophin-deficient mdx mouse, showed no pathological alterations in extraocular muscle. However, mice deficient in both utrophin and dystrophin exhibited severe changes in both the accessory and principal extraocular muscles, with the eye muscles affected more adversely than other skeletal muscles. Selected extraocular muscle fiber types still remained spared, suggesting the operation of an alternative mechanism for muscle sparing in these fiber types. We propose that an endogenous upregulation of utrophin is mechanistic in protecting extraocular muscle in dystrophinopathy. Moreover, data lend support to the hypothesis that interventions designed to increase utrophin levels may ameliorate the pathology in other skeletal muscles in Duchenne muscular dystrophy.
Interphase-specific association of intrinsic centromere protein CENP-C with HDaxx, a death domain-binding protein implicated in Fas-mediated cell death
Authors: Pluta Ann F. , Earnshaw William C. , Goldberg Ilya G. 
Published: April 2021

ABSTRACT
CENP-C, one of the few known intrinsic proteins of the human centromere, is thought to play structural as well as regulatory roles crucial to proper chromosome segregation and mitotic progression. To further define the functions of CENP-C throughout the cell cycle we have used the yeast interaction trap to identify proteins with which it interacts. One specific CENP-C interactor, which we have named HDaxx, was characterized in detail and found to be homologous to murine Daxx, a protein identified through its ability to bind the death domain of Fas (CD95). The interaction between CENP-C and HDaxx is mediated by the amino-terminal 315 amino acids of CENP-C and the carboxyl-terminal 104 amino acids of HDaxx. This region of Daxx is responsible for binding to death domains of several apoptosis signalling proteins. The biological significance of the interaction between CENP-C and HDaxx was confirmed by immunofluorescence colocalization of these two proteins at discrete spots in the nuclei of some interphase HeLa cells. We discuss the functional implications of the interphase-restricted association of HDaxx with centromeres.
Serotonin and the Control of Salivation in the BlowflyCalliphora
Authors: Trimmer Barry Andrew 
Published: April 2021

ABSTRACTThe possibility that serotonin acts as a neurohormone stimulating salivation in the blowfly Calliphora vicina was studied by investigation of salivation induced by injections of high-potassium saline. Induced salivation is rapid and appears to be mediated by an active factor released into the haemolymph (High Potassium Salivary Gland Factor: HKSGF) since it is antagonized by cadmium (a calcium channel blocker) and by gramine (a serotonin-receptor blocker). The action of HKSGF on salivary glands in vitro is indistinguishable from that of serotonin: (a) it generates serotonin-like transepithelial potential changes, (b) its effect on salivation is antagonized by gramine, (c) it is as heat stable as serotonin, (d) it has the same solubility in a variety of organic solvents, (e) it is unaffected by incubation with leucine aminopeptidase or trypsin and (d) it is inactivated by rat liver monoamine oxidase type A (a serotonin deaminating enzyme).Radioenzyme assay of haemolymph from high-potassium injected flies shows that the amount of serotonin present could account for all of the retrievable bioactivity.Significant amounts of serotonin were found in the cerebral ganglion, the thoracic ganglion and nerves attached to the thoracic ganglion. Nerve sectioning experiments demonstrated that the abdominal nerves and the anterior nerves supplying the neck muscles are not involved in the normal salivatory response. However the cerebral-thoracic connective must be intact and it is suggested that release of serotonin is effected close to the main body of the thoracic ganglion. Some of the implications of the neurohormonal role of serotonin are discussed.
Temperature Acclimation of Intestinal Na Transport in the Carp (Cyprinus Carpio L.)
Authors: Gibson J. S. , Ellory J. C. , Cossins A. R. 
Published: April 2021

ABSTRACT
Carp intestine mounted in vitro has a positive serosal potential and a net Na absorption greater than the short-circuit current. At 30°C in vitro, tissues from 10°C-acclimated fish are thought to show heat-damage. When measured at 10°C in vitro, intestine from fish acclimated to 10°C shows a greater rate of sodium transport than that from 30°C-acclimated fish. Mucosal application of amphotericin B, at 10°C in vitro, increases short-circuit current and net Na flux in both 10°C-and 30°C-acclimated fish but does not diminish the difference in Na transport between the two groups, under conditions when the apical membrane permeability is not limiting. It is concluded that the principal acclimatization in carp intestine to low temperature is via an increased basolateral membrane Na pumping capacity.
Cardioactive Peptides From The Cns Of A Caterpillar, The Tobacco Hornworm, Manduca Sexta
Authors: Platt Nicholas , Reynolds Stuart E. 
Published: April 2021

ABSTRACT
A semi-isolated caterpillar heart bioassay was used to detect the presence of endogenous cardioactive material in the CNS of Manduca sexta larvae. Cardioactivity was detected in all nervous tissue examined. Most activity (about 70% of the total in the CNS) was in the ganglia of the abdominal nerve cord (ANC). Cardioactivity was also detected in the abdominal transverse nerves, the proctodeal nerves and the corpora cardiaca/corpora allata. The source with the highest specific activity was the frontal ganglion. Two factors, separable by Sephadex gel filtration, were distinguished in extracts of ANC: CAF 1, which has an estimated relative molecular mass (Mr) of about 4000, and CAF2 for which Mr is probably less than 1000. Both factors are apparently peptides. Neither is similar to any known insect cardioaccelerator. Both CAF 1 and CAF 2 are able to cause cardioacceleration when injected into tetrodotoxin-paralysed caterpillars. CAF 2 is present in both larvae and in adults. CAF 1 is present only in the caterpillar. The larval heart responds to both factors; the adult heart responds only to CAF 2. Partial purification of CAF 1 and CAF 2 by reverse-phase HPLC gives a single peak of bioactivity in each case. The biological activity of CAF 1 is destroyed by a-chymotrypsin, but not by trypsin. CAF 2 is not attacked by trypsin or by a-chymotrypsin. Treatment with performic acid or cyanogen bromide destroys the activity of both CAF 1 and CAF 2.
Respiratory and Cardiovascular Responses of the Exercising Chicken to Spinal Cord Cooling at Different Ambient Temperatures: I. Cardiovascular Responses and Blood Gases
Authors: Barnas G. M. , Gleeson M. , Rautenberg W. 
Published: April 2021

ABSTRACT
We measured oxygen consumption heart rate (HR), stroke volume (SV), cardiac output (CO) and mean arterial blood pressure (MBPa) of chickens during 15 min treadmill exercise at 0·5 ms−1 and 0·8ms−1 at thermoneutral (23°C), low (9°C) and high (34°C) ambient temperature (Ta); the vertebral canal was cooled to 34°C during the middle 5 min of each exercise period. pH and oxygen content of the arterial and mixed venous blood were also measured. during exercise was not significantly affected by Ta. Spinal cord cooling produced definite increases in CO and SV during 0·5ms−1 exercise at 9°C; otherwise, effects of spinal cord cooling were not significant. HR, SV and CO were all linearly related to these relationships were unaffected by spinal cord cooling or Ta. Blood pressure did not increase during exercise. and did not increase significantly during exercise. The arterial-venous difference was increased by exercise only at 34°C. The chickens generally hyperventilated at 34°C Ta compared to the other Ta values. No consistent effect on blood gases or on pH and of the blood could be attributed to spinal cord cooling.