bluuebunny/crossref_metadata_2025_split huggingface dataset:
Protein families in the metazoan genome
Authors: Chothia Cyrus 
Published: April 2021

ABSTRACT
The evolution of development involves the development of new proteins. Estimates based on the initial results of the genome projects, and on the data banks of protein sequences and structures, suggest that the large majority of proteins come from no more than one thousand families. Members of a family are descended from a common ancestor.
Protein families evolve by gene duplication and mutation. Mutations change the conformation of the peripheral regions of proteins; i.e. the regions that are involved, at least in part, in their function. If mutations proceed until only 20% of the residues in related proteins are identical, it is common for the conformational changes to affect half the structure.
Most of the proteins involved in the interactions of cells, and in their assembly to form multicellular organisms, are mosaic proteins. These are large and have a modular structure, in that they are built of sets of homologous domains that are drawn from a relatively small number of protein families. Patthy’s model for the evolution of mosaic proteins describes how they arose through the insertion of introns into genes, gene duplications and intronic recom- bination.
The rates of progress in the genome sequencing projects, and in protein structure analyses, means that in a few years we will have a fairly complete outline description of the molecules responsible for the structure and function of organisms at several different levels of developmental com- plexity. This should make a major contribution to our understanding of the evolution of development.
The evolutionary origin of development: cycles, patterning, Privilege and continuity
Authors: Wolpert L. 
Published: April 2021

ABSTRACT
A scenario for the evolution of a simple spherical multicellular organism from a single eukaryotic cell is proposed. Its evolution is based on environmentally induced alterations in the cell cycle, which then, by the Baldwin effect, become autonomous. Further patterning of this primitive organism -a Blastaea, could again involve environmentally induced signals like contact with the substratum, which could then become autonomous, by, perhaps, cytoplasmic localization and asymmetric cell division. Generating differences between cells based on positional information is probably very primitive, and is well conserved; its relation to asymmetric cell division is still unclear. Differentiation of new cell types can arise from non equivalence and gene duplication. Periodicity also evolved very early on. The origin of gastrulation may be related to mechanisms of feeding.
The embryo may be evolutionarily privileged and this may facilitate the evolution of novel forms.
Larvae are secondarily derived and direct development is the primitive condition as required by the continuity principle.
[3H]Uridine incorporation during previtellogenesis and early vitellogenesis in the oocytes of the chick (Gallus gallus)
Authors: Callebaut Marc 
Published: April 2021

ABSTRACT
During the weeks following hatching of poultry, oocyte differentiation is most advanced in the central part of the ovarian cortex. For instance, in the 5-day-old chicken, oocytes surrounded by a ring of cuboidal cells (constituting early follicles) are appearing in the central part of the cortex. At the extreme periphery of the same cortex one occasionally can find a few germ cells which are still in the late preleptotene, and often all the intermediate stages can be seen at inter-mediate localizations. D’Hollander (1904) has described the different types of oocytes that can be found during the days following hatching. His investigations indicate that during the so-called extrafollicular phase the nucleus probably passes out of pachytene and into a stage when the chromatin is found in heavy filaments split longitudinally in places. Later the cells go through a pseudo-reticular stage in which the nucleoli and the nuclear membrane have reappeared. Between the fifth and the twentieth day after hatching, the intrafollicular phase sets in and the chromatin may also be found in the form of chains (chiasmata), clearly indicating the diplotene stage. From this stage it passes through a granular stage and becomes progressively retracted from the nuclear wall, finally giving ‘barbed’ or lampbrush chromosomes. In the 20-day-old chick, numerous oocyte nuclei with a lampbrush configuration and a large nucleolus can be seen.
Changes in somatic cell nuclei inserted into growing and maturing amphibian oocytes
Authors: Gurdon J. B. 
Published: April 2021

ABSTRACT
When somatic cell nuclei are injected into enucleated unfertilized eggs they very soon cease RNA synthesis (Gurdon & Brown, 1965; Gurdon. 1967a), and commence DNA synthesis (Graham, Arms & Gurdon, 1966). By means of such experiments it has been shown (i) that components of living egg cytoplasm can substantially change the nature of nuclear activity, (ii) that nuclear activity is altered in such a way as to conform to that of the host egg cell, and (iii) that these effects are obtained with the nuclei of adult as well as embryonic cells. The experiments to be reported here were designed to find out whether the same generalizations apply to nuclei inserted into cells other than eggs, and whether they are true of changes in nuclear activity other than the repression of RNA synthesis and the induction of DNA synthesis. For this purpose growing and maturing amphibian oocytes have been used. Growing oocytes are characterized by the very active synthesis of RNA (Brown & Littna, 1964), and by the absence of nuclear DNA synthesis whether [3H]thymidine is supplied intraperitoneally (Izawa, Allfrey & Mirsky, 1963a), or is injected directly into living oocytes (Gurdon, 1967b). Maturing oocytes are in the process of completing meiosis and contain condensed chromosomes inactive in both RNA and DNA synthesis. If cytoplasmic components are of general importance in controlling nuclear activity, it would be predicted that nuclei inactive in RNA synthesis, or unaccustomed to division, should display these activities following insertion, respectively, into growing or maturing oocytes. The results reported here show that this expectation is realized, and permit some general conclusions to be drawn on the widespread importance of the cytoplasmic control of nuclear activity during cell differentiation.
The effect of cold on hind-limb growth and lateral motor column development in Rana pipiens
Authors: Decker R. S. , Kollros J. J. 
Published: April 2021

ABSTRACT
A quantitative correspondence between nerve centers and their peripheral area of innervation has long been inferred from comparative and pathological studies. Many investigations have shown that by varying the mass or number of peripheral structures (1) a hypoplasia or hyperplasia, or (2) a hypotrophy or hypertrophy of their corresponding nerve centers results, indicating that a developmental relationship exists between that periphery and its innervating center. These changes in nerve cell number and size have been demonstrated in a variety of sites, including the spinal cord and spinal ganglia of chicks and amphibians (Piatt, 1948; Hamburger, 1955, 1958; Weiss, 1955).
Differentiation of kidney antigens in the human foetus
Authors: Linder Ewert 
Published: April 2021

ABSTRACT
The appearance of new antigens in the embryo during differentiation has been investigated by a number of authors. Among the proteins studied were myosin (Holtzer, 1961; Ebert, 1962), lens crystallin (Ten Cate & Van Doorenmaalen, 1950), chick embryo haemoglobin (Wilt, 1962), and keratin during feather formation in chick embryo (Ben-Or & Bell, 1965). The development of liver proteins in the chick embryo was studied by D’Amelio, Mutolo & Piazza (1963).
Contractile responses at the surface of an amphibian egg
Authors: Gingell D. 
Published: April 2021

ABSTRACT
During the course of experiments involving the application of polyelectrolytes to amoebae (Gingell, 1967a) it became apparent that highly charged cations are capable of affecting cellular motility. In some circumstances localized applications apparently result in contraction of the cell surface. Korohoda, Forrester, Moreman & Ambrose (1968) subsequently described a reversible charge-dependent response at the surface of isolated amoeba nuclei, which they attributed to nuclear membrane contraction and expansion. Dr Korohoda suggested to me that the surface of Xenopus laevis eggs might be expected to provide a conveniently large experimental system since any contraction would be readily visible.
The lateral line system at metamorphosis in Xenopus laevis (Daudin)
Authors: Shelton Peter M. J. 
Published: April 2021

ABSTRACT
Marked changes in the anatomy of the lateral line system occur during the metamorphosis of Xenopus. The distribution of rows differs in larva and adult and the orientation and number of organs are modified at metamorphosis.
Larval plaques are functional, as shown by recording from their nerves.
Two classes of cells with polarized cilia are present in the tadpole well before the orientation of individual organ plaques is rearranged at metamorphosis.
The topography of the skin surface around individual plaques changes at metamorphosis. This change may reduce the directional sensitivity of organs.
Myelinated inhibitory axons in the lateralis nerve are found only when the tadpole matures. This change takes place at a time when the adult method of locomotion is developed.
The glandular aspects of the tabby syndrome in the mouse
Authors: Grüneberg Hans 
Published: April 2021

ABSTRACT
The tabby syndrome includes abnormalities of the coat and of the sinus hairs, of the teeth, of a multitude of exocrine glands and of some surface structures like tail rings, plicae digitales and the papilla vallata of the tongue. All structures known to be affected by the tabby gene arise by the downgrowth of a surface epithelium into the membrana propria. The involvement of some structures but not of others cannot be accounted for by common origin from one germ layer (as both ectodermal and endodermal derivatives are involved), nor by common function of the structures affected, nor by a time concept such that structures formed before a critical period escape unharmed. The fault may lie either with the surface epithelium, or with the stimuli from the membrana propria which elicit local downgrowth, or with the interaction between the two. It seems least likely that the fault lies with the membrana propria, but a decision cannot be made on the information so far available.
New facts concerning the manifestation of tabby in Ta/+ ♀♀ either lend no support to the ‘inactive X-chromosome’ hypothesis or are at variance with it.
The tabby syndrome is also found in the autosomal genes for crinkled and (presumably) downless.
Morphogenèse trochantérienne provoquée par une régénération fémorale chez le phasme Carausius morosus Br
Authors: Bart Par A. 
Published: April 2021

ABSTRACT
Morphogenesis of the trochanter produced by femoral regeneration in the phasmid Carausius morosus Br.
When the femur of Carausius is cut, about a trochanter’s length from its base, the regenerating limb is made by outgrowths from both the femur and the trochanter.
These two morphogenetic processes may be partly autonomous. The femur can develop into femur, tibia and tarsus while, simultaneously, the trochanter forms femur and tibia. Sometimes the outgrowths form together a femoro-tibial chimera segment whose length is nearly that of a femur or a tibia.
However, in three-quarters of the cases a partial regulation takes place so that a large development of the femoral outgrowth corresponds to a weak development of the trochanteral one. Generally, the longer the initial piece of femur the greater the femoral outgrowth.
The onset of the trochanteral morphogenesis and the relative importance of the trochanteral and femoral outgrowths seem to be related to the degree of distalization of the femoral mass during regeneration.
Age factor in the induced metamorphosis of thyroidectomized tadpoles
Authors: Hsü C. Y. , Yü N. W. , Liang H. M. 
Published: April 2021

ABSTRACT
Three age-groups of thyroidectomized tadpoles of Rana catesbeiana were treated with a series of the same graded increasing concentrations of thyroxin. Normal froglets were formed from the three groups at the end of the induced metamorphosis. Growth and metamorphosis were compared. It was found that while the growth rate was a function of ageing, the pattern and rate of metamorphosis were not affected by senile processes. Therefore a case of differentiation independent of age was presented.
Organ-culture studies of achondroplastic rabbit cartilage: evidence for a metabolic defect in glucose utilization
Authors: Shepard Thomas H. , Bass Glenda L. 
Published: April 2021

ABSTRACT
Organ-culture studies were made using cartilage from achondroplastic (dwarf) rabbits (acfac) and their phenotypically normal litter-mates. A significantly higher incorporation of 14C from glucose and galactose was measured in the dwarf; incorporation of 35S from sulfate and 3H from thymidine was equal in the two types of explant. Also, 14CO2 and [14C]lactate production from glucose by the dwarf cartilage was increased. No difference in the ratio of 14CO2 evolution from [1 -14C]- and [6-14C]glucose was found between the two cartilage types. Explants of dwarf cartilage utilized more glucose from the medium than did the controls.
Radioautographs of tissue sections from the explants showed an increased number of grains from [14 C]glucose overlying the dwarf cartilage, and this difference was particularly great over the central portions of cartilage. The proportion of 14 C grains from glucose was greater over the dwarf nuclei, less over the dwarf matrix and equal over the cytoplasm of the two tissues. Grain counts of sulfate and of thymidine did not differ in the two types of cartilage.
The effects of actinomycin D on the early development of quail and chick embryos
Authors: Billett F. S. , Bowman Patricia , Pugh Doreen 
Published: April 2021

In agreement with previous work it has been found that treatment of chick embryos at an early stage of development with small concentrations of actinomycin D (2·0–4·0 × 108 M) produces abnormalities of the brain, neural tube and somites but allows near normal development of heart and blood islands. Similar effects are produced on quail embryos by even smaller concentrations of actinomycin D (0·8–1·0 x 10−8 M).
In addition to the effect on the embryo, actinomycin D severely restricts the outgrowth of the explanted blastoderm; an effect which becomes obvious after about 8 h culture and coincides with the detachment of the blastoderm edge from the supporting vitelline membrane. Histological examination of the edge of the blastoderm shows that many cells have been killed by the actinomycin D. The pronounced effect of actinomycin D on the growth of the blastoderm cannot be ignored as a factor which causes the embryos to develop abnormally and it is suggested that it may even be the primary cause of the abnormalities. Under these circumstances any interpretation of the effects produced in the embryos in terms of the selective inhibition, or lack of inhibition, of specific messenger RNAs by actinomycin D seems to be unwarranted.
Using [3H]actinomycin D an estimate has been made of the concentration of the compound in the blastoderm tissues at the time when the embryonic abnormalities are produced. The total DNA content of the blastoderms has also been determined. These measurements indicate that the ratio between actinomycin D molecules and guanosine residues in the treated tissue is very low (of the order of 1:20000) and would probably not allow an effective inhibition of DNA-dependent RNA synthesis.
The components of regrowing nerves which support the regeneration of irradiated salamander limbs
Authors: Wallace H. 
Published: April 2021

ABSTRACT
Forelimbs of juvenile axolotls do not regenerate when amputated in a previously irradiated region. They usually do regenerate, however, if they have also been denervated shortly after irradiation and well before amputation. Five series of experiments are reported which define the conditions permitting this paradoxical regeneration.
Crushing the nerves of the brachial plexus proved a satisfactory means of causing temporary denervation. Shielding any region of the arm or shoulder, during an irradiation that preceded such denervation, permits regeneration to occur at a region which was initially irradiated. Lengths of brachial nerve implanted into an irradiated arm also support its regeneration.
It is concluded that temporary denervation (including Wallerian degeneration and the regrowth of axons) mobilizes cells in a shielded region of the arm. These cells migrate both proximally and distally, so that some come to occupy the site of amputation. Schwann cells of the myelin sheath are identified as the cells most likely to behave in this way. It thus seems probable that those non-irradiated Schwann cells which occupy a generally irradiated limb-stump can form the exclusive source of a mesenchymal blastema and the various internal tissues of the regenerate.
Correlation between germinal vesicle and oocyte development in the adult Japanese quail (Coturnix coturnix japónica). A cytochemical and autoradiographic study
Authors: Callebaut Marc 
Published: April 2021

ABSTRACT
Continuity in the various developmental stages of the oocytes in the adult laying Japanese quail may be demonstrated with a method of whole stock labelling of their nuclei by successive applications of [3H]thymidine during their premeiotic period.
Before they mature, the intraovarian oocytes of the adult Japanese quail go through three important successive stages. In each of these stages the chromosomes have a distinct morphology and cytochemical behaviour. During the first stage or prelampbrush chromosome stage, the chromosomes are Feulgen-positive or green after Unna, and on the autoradiographs show intense incorporation of [3H]uridine after injection of this RNA precursor into the animal. During the beginning of this period, which is of very variable duration, the oocyte seems to be in a state of structural stability. The most prominent feature found in the ooplasm of oocytes at this stage is the very large paranuclear Balbiani yolk-body complex, which can be found labelled after injection of [3H]thymidine into the animal. During the second stage or lampbrush chromosome stage, the Feulgen nuclear reaction in the chromosomes weakens or becomes negative and the paranuclear Balbiani yolk-body complex disappears. After Unna, the lampbrush chromosomes and their lateral loops are seen to be pyroninophilic.
On the autoradiographs after intraperitoneal injection of [3H]uridine rapid and intense RNase-sensitive incorporation of this precursor over the chromosomes and nucleoplasm may be noted. During this stage there is thus both cytochemical and autoradiographic evidence for RNA synthesis in the rapidly enlarging germinal vesicle. During the third or postlampbrush stage activity in the germinal vesicle sharply decreases; the volume of the germinal vesicle no longer increases, the very contracted chromosomes are present in the form of Feulgenpositive vacuolized central spherules, and, after intraperitoneal injection of [3H]uridine into the adult laying quail, incorporation cannot be demonstrated in the chromosomes. By contrast, the fundamental part of the ooplasm derived from the cortex, at that moment shows both cytochemical and autoradiographic evidence of the presence and/or synthesis of nucleic acids. The postlampbrush stage is a characteristic feature of non-mature oocytes with a germinal disc and can only be found in regularly laying Japanese quails exposed to full daytime or continuous illumination.
Morbidity of aging non-incubated chicken blastoderms: further cytological evidence and interpretation
Authors: Konishi T. , Kosin I. L. 
Published: April 2021

ABSTRACTCytological analysis was carried out on the blastodermal cells of White Leghorn eggs subjected to several pre-incubation treatments. These treatments were storage, ranging from 0 days to 4 weeks, together with one or more of the following: (1) variation of ambient temperature (5 °C, 15·5 °C, 24 °C), (2) variation of carbon dioxide level (normal air, 1·5% CO2-enriched air), (3) increased humidity (wrapping in plastic bags). To facilitate analysis, the chromosomal configuration of metaphase cells was classified into four types, I–IV, according to their increasingly ‘abnormal’ appearance, which included condensation, dispersal and/or clumping of chromosomes. In interphase cells, the degree of ‘abnormality’ was rated on the staining capacity and shape of the nuclei.The study yielded the following results.Temperature of storage was the most important single factor determining the state of ‘normality’ of the nuclei. The CO2 level in the storage chamber or the use of plastic bags (to provide the eggs in storage with a special ‘ mini-environment ‘, believed largely due to increased humidity) had little effect on the cytological picture of the affected blastoderms. As the blastoderms of eggs stored at 15·5 °C aged, the proportion of Type IV chromosomal configurations steadily rose. At 24 °C the aging process frequently followed a different route: both metaphase and post-metaphase chromosomes often simply disintegrated; the progression from Type I to Type IV was not in evidence. Aging at 5 °C resulted in an early appearance of uniformly dark-stained, spherical or oval nuclei. These were similar to those observed in the terminal stages of retrogression seen in the interphase nuclei. During extended storage at 15·5 °C, mitosis was shown to be blocked at metaphase. No active mitoses were observed in the blastoderms of eggs stored at 5 °C. At 24 °C however, limited mitotic activity was present, up to and including anaphase. The presence or absence of a high level of mitotic activity during pre-incubation storage was not crucial to the survival of the blastoderm. However, an environment that permitted limited mitosis was important if the cells were to have the best possible chance for remaining alive during storage. The CO2 content of the air or the use of plastic bags played no role in this respect. Two explanations, at the nuclear level, are suggested for the observed chain of events in the blastoderm of a stored chicken egg.
The growth of rats and mice vibrissae under normal and some abnormal conditions
Authors: Ibrahim Lamees , Wright E. A. 
Published: April 2021

ABSTRACT
The growth of hair from the mystacial vibrissal follicles of C3H mice and Wistar rats has been measured for up to seven cycles. Normally growth in length and thickness was regular and little affected by age or sex. Plucking vibrissae at any stage during the growing period was followed by the appearance of a new vibrissa 8—11 days later. Plucking when growth had ceased had no effect on the time of appearance of the subsequent cycle. New whiskers emerging after plucking grew at the normal rate. Withholding food slowed the growth of vibrissae within 1 day. Normal growth was re-established 3 days after return to full diet.