bluuebunny/crossref_metadata_2025_split huggingface dataset:
The ASYMMETRIC LEAVES2 gene of Arabidopsis thaliana regulates formation of a symmetric lamina, establishment of venation and repression of meristem-related homeobox genes in leaves
Authors: Semiarti Endang , Ueno Yoshihisa , Tsukaya Hirokazu , Iwakawa Hidekazu , Machida Chiyoko , Machida Yasunori 
Published: April 2021

ABSTRACT
The asymmetric leaves2 (as2) mutant of Arabidopsis thaliana generated leaf lobes and leaflet-like structures from the petioles of leaves in a bilaterally asymmetric manner. Both the delayed formation of the primary vein and the asymmetric formation of secondary veins were apparent in leaf primordia of as2 plants. A distinct midvein, which is the thickest vein and is located in the longitudinal center of the leaf lamina of wild-type plants, was often rudimentary even in mature as2 leaves. However, several parallel veins of very similar thickness were evident in such leaves. The complexity of venation patterns in all leaf-like organs of as2 plants was reduced. The malformed veins were visible before the development of asymmetry of the leaf lamina and were maintained in mature as2 leaves. In vitro culture on phytohormone-free medium of leaf sections from as2 mutants and from the asymmetric leaves1 (as1) mutant, which has a phenotype similar to that of as2, revealed an elevated potential in both cases for regeneration of shoots from leaf cells. Analysis by the reverse transcription-polymerase chain reaction showed that transcripts of the KNAT1, KNAT2 and KNAT6 (a recently identified member of the class 1 knox family) genes accumulated in the leaves of both as2 and as1 plants but not of wild type. Transcripts of the STM gene also accumulated in as1 leaves. These findings suggest that, in leaves, the AS2 and AS1 genes repress the expression of these homeobox genes, which are thought to maintain the indeterminate cell state in the shoot apical meristem. Taken together, our results suggest that AS2 and AS1 might be involved in establishment of a prominent midvein and of networks of other veins as well as in the formation of the symmetric leaf lamina, which might be related to repression of class 1 knox homeobox genes in leaves.
Gene expression profiles inCiona intestinalistailbud embryos
Authors: Satou Yutaka , Takatori Naohito , Yamada Lixy , Mochizuki Yasuaki , Hamaguchi Makoto , Ishikawa Hisayoshi , Chiba Shota , Imai Kaoru , Kano Shungo , Murakami Seiko D. , Nakayama Akie , Nishino Atsuo , Sasakura Yasunori , Satoh Gohki , Shimotori Taishin , Shin-i Tadasu , Shoguchi Eiichi , Suzuki Miho M. , Takada Norio , Utsumi Nanami , Yoshida Natsue , Saiga Hidetoshi , Kohara Yuji , Satoh Nori 
Published: April 2021

A set of 3423 expressed sequence tags derived from the Ciona intestinalis tailbud embryos was categorized into 1213 independent clusters. When compared with DNA Data Bank of Japan database, 502 clusters of them showed significant matches to reported proteins with distinct function, whereas 184 lacked sufficient information to be categorized (including reported proteins with undefined function) and 527 had no significant similarities to known proteins. Sequence similarity analyses of the 502 clusters in relation to the biosynthetic function, as well as the structure of the message population at this stage, demonstrated that 390 of them were associated with functions that many kinds of cells use, 85 with cell-cell communication and 27 with transcription factors and other gene regulatory proteins. All of the 1213 clusters were subjected to whole-mount in situ hybridization to analyze the gene expression profiles at this stage. A total of 387 clusters showed expression specific to a certain tissue or organ; 149 showed epidermis-specific expression; 34 were specific to the nervous system; 29 to endoderm; 112 to mesenchyme; 32 to notochord; and 31 to muscle. Many genes were also specifically expressed in multiple tissues. The study also highlighted characteristic gene expression profiles dependent on the tissues. In addition, several genes showed intriguing expression patterns that have not been reported previously; for example, four genes were expressed specifically in the nerve cord cells and one gene was expressed only in the posterior part of muscle cells.This study provides molecular markers for each of the tissues and/or organs that constitutes the Ciona tailbud embryo. The sequence information will also be used for further genome scientific approach to explore molecular mechanisms involved in the formation of one of the most primitive chordate body plans.
The electron microscopy and cytochemistry of oogenesis and the cytochemistry of embryonic development of the prosobranch gastropodBembicium nanumL.
Authors: Bedford Lynne 
Published: April 2021

ABSTRACTEmbryonic development in B. nanum is similar to that of Littorina obtusa, apart from differences, especially in the velum and foot, which can be correlated with the planktonic mode of life of the veliger of B. nanum. Electron microscope studies of oogenesis show that fatty yolk formation occurs in association with the vitelline body and with mitochondria, and proteid yolk formation occurs in association with the Golgi apparatus. Nucleo-cytoplas-mic relationships in the growing oocyte are discussed. During oogenesis, cytochemical localizations can be related to the nucleolar activity, elaboration of the endoplasmic reticular elements and the presence of yolk. No preferential distribution of the substances tested occurs in the cytoplasm of the late oocyte. Following fertilization, slight animal-vegetal and radial gradients are established, chiefly in association with the yolk. During cleavage, a definite animal-vegetal gradient is seen in the pattern of cytochemical localizations, but the differences between the cells are only relative, no rigid localizations in one cell or group of cells occurring. During gastrulation, the chemo-differentiation detectable in early embryonic development is well established. The cells of the ectoderm, endoderm and mesoderm are each cytochemically distinct, but no absolute distinctions between each cell type can be shown. During organogenesis, the initial differentiation of both larval and adult cells is accompanied by strongly positive reactions for DNA, RNA and alkaline phosphatase in these cells. Following this initial differentiation, two distinct cell types emerge : (i) Functional larval cells (both ectodermal and endodermal) involved in nutrition and locomotion, showing slight reactions for RNA, DNA and alkaline phosphatase (except where these are involved in cell function) and highly positive reactions for iron, glycogen and PAS-positive material. (ii) Adult rudiment cells, which may be functional in the larva, but are still differentiating towards the adult type and remain strongly positive for DNA, RNA and alkaline phosphatase.
Observations on some tumours found in two species of planaria—Dugesia etrusca and D. ilvana
Authors: Lange C. S. 
Published: April 2021

ABSTRACT
Since the description by Pallas in 1774 of their remarkable capacity for regeneration the planarians have been of interest to the biologist (cf. Brøndsted’s excellent review— Brøndsted, 1955). Dubois (1949) has shown that regeneration in planaria is due to undifferentiated totipotential cells referred to as neoblasts, which are the only cells known to divide mitotically. When the animal is cut or similarly injured, some neoblasts in the region of the wound rapidly differentiate to form a new epidermis, while other neoblasts divide and migrate towards the wound surface where they continue to divide and/or differentiate into various cell types. The finding of spontaneous growths or tumours in this simple material (Goldsmith, 1939) suggests that it may be of interest to study the nature of such tumours.
Formation de cytasters dans les œufs de Batraciens sous l’action de l’eau lourde
Authors: van Assel S. , Brachet J. 
Published: April 2021

ABSTRACT
Des travaux récents de Gross et de ses collaborateurs (Gross & Spindel, 1960 a, b; Gross & Cousineau, 1963; Gross, Spindel & Cousineau, 1963,1964) ont montré que la formation de cytasters, dans le cytoplasme des œufs vierges d’oursins, s’obtient aisément par un traitement avec de l’oxyde de deuterium (eau lourde : D2O). A haute concentration, l’eau lourde agit comme un agent parthéno-génétique.
The morphology and timing of fertilization and early cleavage in the Mongolian gerbil and Deer mouse
Authors: Marston J. H. , Chang M. C. 
Published: April 2021

ABSTRACTOvulation, fertilization and early cleavage have been investigated in few myomorph rodents and in only two members of the family Cricetidae. The Golden hamster (subfamily Cricetinae: Mesocricetus auratus) was studied by Graves (1945), Venable (1946a, b), Ward (1948), Strauss (1956) and Harvey, Yanagimachi & Chang (1961), using fixed and stained materials; and Austin (1956a), Samuel & Hamilton (1942) and Hamilton & Samuel (1956) examined the living eggs. The effects of delayed fertilization were investigated by Chang & Fernandez-Cano (1958) and Yanagimachi & Chang (1961). The Field vole (subfamily Microtinae: Microtus agrestis) was studied by Austin (1957).
The effects of erythropoietin on haem synthesis in mouse yolk sac and cultured foetal liver cells
Authors: Cole R. J. , Paul John 
Published: April 2021

ABSTRACT
Erythropoiesis in the foetal mouse is reported to occur initially in the yolk sac, followed by the liver, the spleen and finally the bone marrow (Snell, 1956; Borghese, 1959). At 12 days of gestation 97 % of the circulating erythrocytes are nucleated (Craig & Russell, 1964) and presumably arise from the yolk sac blood islands. The cells of this generation persist in decreasing numbers until the 16th day of gestation. Haemoglobin can first be recognized by histochemical methods (O’Brien, 1961) in the yolk sac before somite formation at the early head fold stage and a network of blood islands, almost covering the embryo, rapidly develops (Plate 1, figs. A–F)’
Developmental effects of chronic maternal audiovisual stress on the rat fetus
Authors: Geber William F. 
Published: April 2021

ABSTRACT
Pregnant Sprague-Dawley albino rats were subjected to controlled audiovisual stress throughout pregnancy. The total effective stress duration amounted to 10 % (6 min) of every hour of the entire day. Total litter resorption occurred in 40 and 50 % of the pregnancies in the young and older females respectively. Litter size was reduced by an average of two fetuses per litter in both age-groups. Visible resorptions per litter were markedly increased in the young females and slightly reduced in the older females. Developmental abnormalities produced included interparietal meningocele, abdominal hernia (omphalocele), spina bifida, and defects of the eye, tail, hind- and forefoot. Hematomas, varying in size and location, were found throughout the cranial area. Localized hematomas were found in the sublingual areas. Osteogenic effects, ranging from partial to complete inhibition, were widespread. There was a marked increase in number and degree of hypo- and hyperdeveloped fetuses over the control rate. Total number of fetuses manifesting some type of developmental deviation amounted to 25 % of the experimental groups and 0-8 % of the control groups. Effects of the audiovisual stress on the maternal organism included slight body-weight loss in both young and older females, decrease in the weight of the adrenals, kidneys, and hearts of the younger females, and increase in organ weight, especially the heart, in the older females. The etiological factors postulated to be responsible for the fetal results are (1) decreased uterine and fetal organ blood flow, and (2) imbalance of the maternal autonomic neurohormone and hypothalamic-pituitary-adrenal relationships.
Studies on pattern regulation in hydra
Authors: Webster Gerald 
Published: April 2021

ABSTRACT
The factors controlling hypostome formation in hydra have been investigated using transplantation techniques. Two factors have been demonstrated, (a) inhibition of hypostome formation and (b) threshold for inhibition. The presence of a hypostome inhibits the formation of another hypostome. This confirms the results of other workers. Inhibition can act in either a disto-proximal or a proximo-distal direction. The level of inhibition is lower in proximal than in distal regions, i.e. the level or effectiveness of inhibition declines as the distance from the hypostome increases. An axial gradient in level of inhibition is postulated. The difference in behaviour of regions from different axial positions when transplanted to the basal disc, i.e. when subjected to identical inhibiting conditions, indicated that regions have different thresholds for inhibition. Distal regions have higher thresholds than proximal regions; an axial gradient in threshold is postulated. The idea of a threshold for inhibition is a new concept as far as regulation in hydroids is concerned. The interaction between threshold and level of inhibition is believed to control hypostome formation. Polarized regulation of hydra into a distal hypostome and a proximal non-hypostomal region is discussed in terms of these concepts. The results are discussed in relation to those obtained by other workers on other hydroids. Re-interpretation of these results suggests that inhibition and threshold are controlling factors in the regulation of other hydroids.
Acid mucopolysaccharides in the development of the Pacific great skate, Raja binoculata
Authors: Mcconnachie P. R. , Ford P. 
Published: April 2021

ABSTRACT
Histochemical treatments specific for hyaluronic acid, C-S-A/C, C-S-B and heparin were applied to a series of Pacific great skate (Raja binoculata) embryos from cleavage to immediate prehatching stages, in order to characterize histochemically the AMPS present in the embryos and to study the events leading to AMPS localization in the adult. A progression was observed: (a) intracellular neutral polysaccharides in cleavage stages, (b) a combination of extracellular polysaccharides and weakly acidic AMPS (hyaluronic acid) associated with cell processes in neurulating stages, (c) extracellular strongly acidic AMPS (chondroitin sulphates) in later stages, particularly in areas of cartilage development. In neurulating embryos hyaluronic acid appeared in quantity between adjacent tissues, suggestive of some developmental significance for this compound. Hyaluronic acid also appeared after neurulation in close association with developing gut and mesonephros. Histochemical localization of these compounds in immediate prehatching stages agreed with previously reported biochemical analyses of shark skin and cartilage, i.e. C-S-B occurred in skin and C-S-A/C was a major component of cartilage matrix.
The relationship of chemical structure to teratogenic activity among bisazo dyes: a re-evaluation
Authors: Lloyd J. B. , Beck F. 
Published: April 2021

ABSTRACT
Samples of five bisazo dyes, trypan blue, Niagara blue 2B, Niagara blue 4B, Afridol blue and Evans blue, of confirmed identity and known purity, have been tested as teratogens by suebutaneous injection into the Wistar rat. Each dye except Niagara blue 4B, if administered at an appropriate dose and stage of pregnancy, shows high activity. Niagara blue 4B at low dose produces a few malformed survivors at term, but in higher doses leads to considerable maternal and embryonic mortality. Serum dye concentrations at intervals after subcutaneous injection were calculated and it was found that when injected at doses which gave maximum teratogenic response serum levels of the same order over the susceptible period were maintained for each dye. The hypothesis is advanced that the observed differences in teratogenic behaviour of the dyes to some extent reflect differences in the handling of the dyes by the mother rather than absolute differences in activity.
On the pars distalis hormone activities involved in spleen development in chicken embryos
Authors: Hart D. E. , Betz T. W. 
Published: April 2021

ABSTRACTSpleen development was studied in 11 groups of chicken embryos: (1) intact, I; (2) ‘hypo-physectomized H, by partial decapitation, and nine groups of ‘hypophysectomized’ embryos in which each host received a specific type of pars distalis graft; (3) one cephalic region, HCe; (4) one middle region, HM;, (5) one caudal region, HCa;, (6) the entire pars distalis, HE; (7) two cephalic regions, H2Ce; (8) two middle regions, H2M;, (9) two caudal regions, H2Ccr; (10) one cephalic and one caudal region, HCeCcr. or (11) one cephalic, one middle and one caudal region, HCeMCa. Embryos were killed at 20-5 days of incubation. Levels of spleen development were assessed by changes in mean weight and histogenesis.Spleen development in ‘hypophysectomized’ embryos was normal only with cephalic and middle region pars distalis grafts but not with caudal grafts. Grafts of entire partes distales or of two cephalic regions were no more effective than single cephalic regions in correcting development. Double caudal region grafts were as ineffective as single caudal region grafts. Apparently there are qualitative differences between pars distalis regions. Cephalic and middle grafts probably produced sufficient ACTH and TSH activities to stimulate adequate levels of adrenocorticoids and thyroid hormone and perhaps prolactin to repair spleen development. These may be the only hormones important for spleen development, because caudal graft ineffectiveness suggests that STH is unnecessary and may not be involved.
Cytodynamics and ontogeny of the immune reponse ofXenopus laevisagainst sheep erythrocytes
Authors: Kidder Gerald M. , Ruben Laurens N. , Stevens Jean M. 
Published: April 2021

ABSTRACTThe heterologous red cell response of Xenopus laevis larvae and post-metamorphic toadlets was investigated by means of the immuno-cytoadherence (ICA) technique. Sheep erythrocytes (SRBC) were employed as immunogen.Toadlets responded to a single injection of immunogen within 4 days, and exhibited a peak level of rosette-forming cells (RFC) in their spleens at 8 days post-injection. Toadlets immunized against sheep erythrocytes gave only a very slight response when tested against rat erythrocytes. A secondary response, much greater in magnitude than the primary re-sponse, wasevident within 2days when previously immunized toadlets were reinjected with the same immunogen. It was concluded that the ICA technique provides a quantitative measure of an acute immune response in these animals.Larvae which had passed through stage 50 of Nieuwkoop & Faber exhibited substantial increases in RFC in the spleens when tested 6-10 days after injection with sheep erythrocytes. Significantly increased frequencies of RFC in thymi were also noted in these larvae, but the numbers involved were very low and varied considerably. Histological observations of these larvae revealed lymphoid maturation of the spleens and thymi to be essentially complete.Larvae which had not reached stage 50 according to external morphological criteria, but whose lymphoid organs had matured to a degree equivalent to stage 50, also exhibited strong anti-SRBC response in the spleens. Response in the thymi was low and not statistically significant. Larvae injected at a stage when lymphocytic differentiation was complete in the thymi but had not begun in the spleens did not exhibit an elevated splenic RFC frequency when tested after the spleens had matured. These data suggest that the heterologous red cell response in the larval spleen is dependent upon antigenic challenge to spleens which have reached the stage 50 equivalent in their histogenesis.
Nuclear transplantation with melanophores, ciliated epidermal cells, and the established cell-line A-8 inXenopus laevis
Authors: Kobel H. R. , Brun R. B. , Fischberg M. 
Published: April 2021

ABSTRACTThe developmental potencies of melanophores, ciliated epidermal cells and cells from an established line were tested by means of nuclear transplantation into enucleated Xenopus eggs. Donor nuclei from ciliated epidermal cells of hatching tadpoles never gave rise, after transplantation, to development beyond the blastula stage; nuclei from non-ciliated cells of the same larvae, on the other hand, could fully replace a zygote nucleus. Melanophore nuclei taken from the tailfin of advanced larvae (stage 56) gave rise to blastulae and, in one case, an incipient invagination was observed. Melanophore nuclei taken from tissue cultures, set up from hatching tadpoles, proved to be competent for leading development as far as the heartbeat stage, (stage 33/34), the embryo showing well-elaborated eye Anlagen, muscles, notochord, cement gland, etc. Nuclei from the highly aneuploid established cell-line A-8 were able to give rise to hatching-stage embryos. These results suggest that some condition, provided by culturing, influences the differentiated state so as to improve the chances of the donor nucleus co-operating with the egg’s developmental programme. The important change might be the state of proliferation attained in cultured cells.
Etude des duplications encéphaliques chez l’embryon de Poulet par implantation de mésoderme ventral présomptif
Authors: Vein D. 
Published: April 2021

ABSTRACTStudy of the encephalic duplications produced in the chick embryo by implantation of presumptive ventral mesoderm in the node areaMaterial from the posterior third of the primitive streak has been implanted in place of Hensen’s node or in its close vicinity. Implants of embryonic haemopoietic tissues were also used as well as inert material (agar) for controls.The replacement of Hensen’s node by yet-undifferentiated material (even lateral to the streak) leads to encephalic twinning.The implantation of the same material in a paraxial location leads to various results extending from normal cephalogenesis to encephalic twinning.There is no effect from the same material when implanted in front of Hensen’s node or behind it, nor is there an effect from other materials when implanted into the node.It is concluded that the ventral material leads to twinning owing to its ability to participate in the morphogenetic movements of the neighbouring territories, while modifying them, and to form dorsal structures under their influence.
Sex differentiation of the gonad of fry transplanted into the anterior chamber of the adult eye in the teleost,Oryzias latipes
Authors: Satoh Noriyuki 
Published: April 2021

ABSTRACTIn order to examine whether or not sex differentiation in the medaka, Oryzias latipes, is modified by the physiological level of sex hormones in the adult fish, trunk regions containing the gonads of newly hatched fry were transplanted unilaterally into the anterior chamber of the eyes of adult fish.The grafts could be classified into two types according to the vascularization. One type of graft developed well ; some of them protruded from the eyes of the host fish. In these grafts the connexion of the blood circulation between the graft and the host was detectable without exception. The other type of graft consisted of those specimens without vascularization. The grafts of this type did not grow in size; this condition seemed to be similar to the so-called in vivo culture in the anterior chamber of the eye in rodents. Most of these grafts, however, degenerated.Judging from the histology of the gonad in the graft, a genetic male graft in the eye of a fish developed into a testis, regardless of the sexuality of the host. This fact was confirmed by two series of experiments. The gonad of a genetic female fry developed into an ovary if the graft was transplanted into a female fish. On the other hand, the gonad of a genetic female graft transplanted into a male fish failed to develop into an ovary, but formed spermatogenetic cells in a gonad of an abnormal structure.Therefore, it is highly probable that the reversal of sex differentiation from genetic oogonia into spermatogenetic cells is accomplished by the physiological level of the sex hormones in male fish. On the contrary, the sex reversal of genetic males to females is not induced by the physiological level of female sex hormones.