scholarly journals SPECIFIC GRANULES IN ATRIAL MUSCLE CELLS

1964 ◽  
Vol 23 (1) ◽  
pp. 151-172 ◽  
Author(s):  
J. D. Jamieson ◽  
G. E. Palade
Keyword(s):  
Acid Phosphatase ◽  
Golgi Complex ◽  
Muscle Fibers ◽  
Small Population ◽  
Intimate Association ◽  
Large Populations ◽  
Lipofuscin Pigment ◽  
Residual Bodies ◽  
Glycogen Particles ◽  
Newborn Animals

Large populations (up to 600/cell) of spherical, electron-opaque granules ∼0.3 to 0.4 µ in diameter are characteristically found in muscle fibers of mammalian atria. They are absent in muscle fibers of the ventricles. The granules are concentrated in the sarcoplasmic core and occur in lesser numbers in the sarcoplasmic layers between myofibrils and under the plasma membrane. Their intimate association with a central voluminous Golgi complex and the frequent occurrence of material reminiscent of the granular content within the cisternae of the Golgi complex suggest that the latter is involved in the formation of the atrial granules. Atrial granules are larger and more numerous in smaller species (rat, mouse), and generally smaller and less numerous in larger mammals (dog, cat, human); they are absent from the atrial fibers of very young fetuses (rat) but are present in those of newborn animals. A small population of bodies containing glycogen particles and remnants of the endoplasmic reticulum and mitochondria occurs in the sarcoplasmic cores of atrial as well as ventricular muscle fibers in the rat; they contain acid phosphatase and thus appear to be residual bodies of autolytic foci. Their frequency increases with the age of the animal. Typical lipofuscin pigment granules, which are known to contain acid phosphatase and are found in the sarcoplasmic cores in old animals (cat, dog and human), are presumed to arise by progressive aggregation and fusion of small residual bodies.

Demonstration of Secondary Lysosomes in Bovine Megakaryocytes and Platelets Using Acid Phosphatase Cytochemistry with Cerium as a Trapping Agent

1990 ◽  
Vol 63 (01) ◽  
pp. 127-132 ◽  
Author(s):  
Michèle Ménard ◽  
Kenneth M Meyers ◽  
David J Prieur
Keyword(s):  
Acid Phosphatase ◽  
Electron Density ◽  
Golgi Complex ◽  
Initial Report ◽  
Cerium Phosphate ◽  
Virtual Absence ◽  
Phosphatase Cytochemistry ◽  
Secondary Lysosomes ◽  
Trapping Agent

SummaryThe ultrastructure of lysosomes from bovine megakaryocytes (MK) and platelets was characterized using acid phosphatase cytochemistry with beta-glycerophosphate as substrate and cerium as a trapping agent. The technique was easily reproducible; cerium-phosphate precipitates were uniform, readily visualized, and there was a virtual absence of nonspecific reaction product. Acid phosphatase was localized in the trans aspect of the Golgi complex and/or granules of less than 50 nm to 650 nm diameters in MK at all stages of maturation. Forty percent of the MK lysosomes contained inclusions of variable shapes, sizes and electron-density and were classified as secondary lysosomes. Twenty-four percent of the platelet sections contained acid phosphatase-positive granules. Fifty-four percent of these were secondary lysosomes. This is the initial report demonstrating secondary lysosomes in either resting MK or platelets using acid phosphatase cytochemistry. These findings suggest that MK and platelet lysosomes have an intracellular function in resting MK and platelets.

scholarly journals LOCALIZATION OF PEROXIDASE ACTIVITY IN MICROBODIES OF FETAL MOUSE LIVER

1969 ◽  
Vol 17 (7) ◽  
pp. 454-466 ◽  
Author(s):  
EDWARD ESSNER
Keyword(s):  
Electron Microscopy ◽  
Endoplasmic Reticulum ◽  
Acid Phosphatase ◽  
Peroxidase Activity ◽  
Mouse Liver ◽  
Fetal Liver ◽  
Light And Electron Microscopy ◽  
Small Population ◽  
Fetal Mouse ◽  
Fetal Mouse Liver

The peroxidase activity of microbodies in fetal mouse liver was studied by light and electron microscopy. Two types of microbodies were present; a small population of bodies that lacked a nucleoid, predominant on the 16th day of gestation, and a larger population of nucleoid-bearing microbodies, predominant on the 19th day, in association with the rough endoplasmic reticulum from which they probably originate. Both types of bodies were visualized when incubated for peroxidase activity but were negative (19th day) for acid phosphatase activity. The findings suggest that the anucleoid- and nucleoid-bearing organelles together constitute the microbody population of the fetal liver.

scholarly journals Evolution of Drift Robustness in Small Populations

2016 ◽  
Author(s):  
Thomas LaBar ◽  
Christoph Adami
Keyword(s):  
Mathematical Modeling ◽  
Experimental Evolution ◽  
Small Population ◽  
Small Populations ◽  
Mutational Load ◽  
Deleterious Mutations ◽  
Mutational Robustness ◽  
Large Populations ◽  
Slightly Deleterious Mutations ◽  
Population Sizes

AbstractMost mutations are deleterious and cause a reduction in population fitness known as the mutational load. In small populations, weakened selection against slightly-deleterious mutations results in an additional fitness reduction. Many studies have established that populations can evolve a reduced mutational load by evolving mutational robustness, but it is uncertain whether small populations can evolve a reduced susceptibility to drift-related fitness declines. Here, using mathematical modeling and digital experimental evolution, we show that small populations do evolve a reduced vulnerability to drift, or “drift robustness”. We find that, compared to genotypes from large populations, genotypes from small populations have a decreased likelihood of small-effect deleterious mutations, thus causing small-population genotypes to be drift-robust. We further show that drift robustness is not adaptive, but instead arises because small populations preferentially adapt to drift-robust fitness peaks. These results have implications for genome evolution in organisms with small population sizes.

scholarly journals Changes in architecture of the Golgi complex and other subcellular organelles during myogenesis.

1993 ◽  
Vol 120 (2) ◽  
pp. 399-409 ◽  
Author(s):  
E Ralston
Keyword(s):  
Protein Synthesis ◽  
Golgi Complex ◽  
Secretory Pathway ◽  
Muscle Fibers ◽  
Spatial Relationship ◽  
Mouse Muscle ◽  
Subcellular Organelles ◽  
Flexor Digitorum Brevis

Myogenesis involves changes in both gene expression and cellular architecture. Little is known of the organization, in muscle in vivo, of the subcellular organelles involved in protein synthesis despite the potential importance of targeted protein synthesis for formation and maintenance of functional domains such as the neuromuscular junction. A panel of antibodies to markers of the ER, the Golgi complex, and the centrosome were used to localize these organelles by immunofluorescence in myoblasts and myotubes of the mouse muscle cell line C2 in vitro, and in intact single muscle fibers from the rat flexor digitorum brevis. Antibodies to the ER stained structures throughout the cytoplasm of both C2 myoblasts and myotubes. In contrast, the spatial relationship between nucleus, centrosome, and Golgi complex was dramatically altered. These changes could also be observed in a low-calcium medium that allowed differentiation while preventing myoblast fusion. Muscle fibers in vivo resembled myotubes except that the ER occupied a smaller volume of cytoplasm and no staining was found for one of the Golgi complex markers, the enzyme alpha-mannosidase II. Electron microscopy, however, clearly showed the presence of stacks of Golgi cisternae in both junctional and extrajunctional regions of muscle fibers. The perinuclear distribution of the Golgi complex was also observed in live muscle fibers stained with a fluorescent lipid. Thus, the distribution of subcellular organelles of the secretory pathway was found to be similar in myotubes and muscle fibers, and all organelles were found in both junctional and extrajunctional areas of muscle.

scholarly journals Population size influences the type of nucleotide variations in humans

BMC Genetics ◽  
2019 ◽  
Vol 20 (1) ◽  
Author(s):  
Sankar Subramanian
Keyword(s):  
Population Size ◽  
Effective Population Size ◽  
High Frequency ◽  
Genetic Diseases ◽  
Large Population ◽  
Low Frequency ◽  
Small Population ◽  
Effective Population ◽  
Genome Data ◽  
Large Populations

Abstract Background It is well known that the effective size of a population (Ne) is one of the major determinants of the amount of genetic variation within the population. However, it is unclear whether the types of genetic variations are also dictated by the effective population size. To examine this, we obtained whole genome data from over 100 populations of the world and investigated the patterns of mutational changes. Results Our results revealed that for low frequency variants, the ratio of AT→GC to GC→AT variants (β) was similar across populations, suggesting the similarity of the pattern of mutation in various populations. However, for high frequency variants, β showed a positive correlation with the effective population size of the populations. This suggests a much higher proportion of high frequency AT→GC variants in large populations (e.g. Africans) compared to those with small population sizes (e.g. Asians). These results imply that the substitution patterns vary significantly between populations. These findings could be explained by the effect of GC-biased gene conversion (gBGC), which favors the fixation of G/C over A/T variants in populations. In large population, gBGC causes high β. However, in small populations, genetic drift reduces the effect of gBGC resulting in reduced β. This was further confirmed by a positive relationship between Ne and β for homozygous variants. Conclusions Our results highlight the huge variation in the types of homozygous and high frequency polymorphisms between world populations. We observed the same pattern for deleterious variants, implying that the homozygous polymorphisms associated with recessive genetic diseases will be more enriched with G or C in populations with large Ne (e.g. Africans) than in populations with small Ne (e.g. Europeans).

scholarly journals Slower environmental change hinders adaptation from standing genetic variation

2017 ◽  
Author(s):  
Thiago S. Guzella ◽  
Snigdhadip Dey ◽  
Ivo M. Chelo ◽  
Ania Pino-Querido ◽  
Veronica F. Pereira ◽  
...  
Keyword(s):  
Genetic Variation ◽  
Environmental Change ◽  
Environmental Changes ◽  
Extreme Environment ◽  
Small Population ◽  
Population Bottlenecks ◽  
Genotype By Environment ◽  
Standing Variation ◽  
Large Populations ◽  
Population Sizes

AbstractEvolutionary responses to environmental change depend on the time available for adaptation before environmental degradation leads to extinction. Explicit tests of this relationship are limited to microbes where adaptation depends on the order of mutation accumulation, excluding standing genetic variation which is key for most natural species. When adaptation is determined by the amount of heritable genotype-by-environment fitness variance then genetic drift and/or maintenance of similarly fit genotypes may deter adaptation to slower the environmental changes. To address this hypothesis, we perform experimental evolution with self-fertilizing populations of the nematode Caenorhabditis elegans and develop a new inference model that follows pre-existing genotypes to describe natural selection in changing environments. Under an abrupt change, we find that selection rapidly increases the frequency of genotypes with high fitness in the most extreme environment. In contrast, under slower environmental change selection favors those genotypes that are worse at the most extreme environment. We further demonstrate with a second set of evolution experiments that, as a consequence of slower environmental change, population bottlenecks and small population sizes lead to the loss of beneficial genotypes, while maintenance of polymorphism impedes their fixation in large populations. Taken together, these results indicate that standing variation for genotype-by-environment fitness interactions alters the pace and outcome of adaptation under environmental change.

scholarly journals LOCALIZATION OF ACID PHOSPHATASE IN LIPOFUSCIN GRANULES AND POSSIBLE AUTOPHAGIC VACUOLES IN INTERSTITIAL CELLS OF THE GUINEA PIG TESTIS

1968 ◽  
Vol 36 (1) ◽  
pp. 1-13 ◽  
Author(s):  
Arthur L. Frank ◽  
A. Kent Christensen
Keyword(s):  
Acid Phosphatase ◽  
Guinea Pig ◽  
Intracellular Localization ◽  
Interstitial Cells ◽  
Chemical Mechanism ◽  
Autophagic Vacuoles ◽  
Pigment Granules ◽  
The Matrix ◽  
Lipofuscin Pigment ◽  
Testicular Interstitial Cells

The intracellular localization of acid phosphatase in guinea pig testicular interstitial cells was investigated by incubating nonfrozen thick sections of glutaraldehyde-perfused testis in a modified Gomori medium and preparing the tissue for electron microscopy. Lipofuscin pigment granules in these cells contain dense pigment, granular matrix, and often a lipid droplet. Reaction product is seen in the matrix of the pigment granules, and they may therefore be called residual bodies. At least some of the dense pigment appears to be derived from myelin figures and membrane whorls, since suitable intermediates can be seen. Lipid droplets found free in the cytoplasm are another possible source of pigment. In both cases the chemical mechanism is presumed to be autoxidation of unsaturated lipid. Acid phosphatase is present in the inner cisterna of Golgi elements. Enzyme activity also appears in possible autophagic vacuoles bounded by double membranes; the reaction product lies between the membranes. Consideration of the enzyme as a tracer suggests that the autophagic vacuoles are derived from the Golgi complex. Possible stages in the formation of these vacuoles by the inner Golgi cisternae are observed.

The Rise and Fall of Zimbabwe

1972 ◽  
Vol 13 (3) ◽  
pp. 353-366 ◽  
Author(s):  
T. N. Huffman
Keyword(s):  
State Formation ◽  
Iron Age ◽  
Small Population ◽  
Immigrant Group ◽  
Primary State ◽  
Social Transition ◽  
African Society ◽  
Large Populations ◽  
Age Sequence ◽  
Secondary State

Two hypotheses are available for the origin of the Zimbabwe culture. A religious hypothesis attributes its development to an African society in isolation, placing it in the class of a primary state. In contrast, the trade hypothesis maintains that it was a secondary state resulting from the gold trade.If the religious hypothesis is correct, then Zimbabwe would be an exception to all other known cases of primary state formation. The archaeological evidence points to a horticultural subsistence throughout the Iron Age sequence in the area and a small population until Period III/IV. On the other hand, all known primary states were based on large populations and intensive agriculture. It is more likely that Zimbabwe is a typical case of secondary state formation.The stratigraphy on the Acropolis indicates that a social transition from Period II to III probably occurred at Zimbabwe and was not the result of an immigrant group, and the short chronology places this transition around A.D. 1250. The evidence available from Arab documents, trade imports and ancient mining demonstrates that trade existed well before then. Consequently, the evolution of the Zimbabwe culture was almost certainly due to the Arab gold trade.

Origin and cytochemistry of the animal dimple granules in Discoglossus pictus (Anura) eggs

Development ◽  
1980 ◽  
Vol 56 (1) ◽  
pp. 239-252
Author(s):  
Piero Andreuccetti ◽  
Chiara Campanella
Keyword(s):  
Acid Phosphatase ◽  
Golgi Complex ◽  
Fibrous Material ◽  
Cortical Region ◽  
Cortical Granules ◽  
The Core ◽  
Discoglossus Pictus ◽  
Electron Dense Core ◽  
Peripheral Cytoplasm ◽  
Macromolecular Content

At the centre of the animal hemisphere of the 1000µm ovarian oocytes of Discoglossus pictus there is the germinative area, a slightly depressed disc, 700 µm wide. During thepassage of the oocyte through the oviduct this area becomes invaginated to form the ‘animal dimple’, which is the only site where successful sperm entrance can occur. Granules (G) with a central electron-dense core and a peripheral portion containing sparse fibrous material are found in the peripheral cytoplasm of the animal dimple. The origin and the cytochemistry of G's have been investigated. G's originate from Golgi complexes located in the peripheral cytoplasm of the germinative area only. Recently formed G's migrate to the oocyte cortical region, where vesicles appear to participate in G's maturation. The core of G's can be digested by pronase, is negative to a test for acid phosphatase detection, and contains a few polysaccharide complexes. In view of their origin from Golgi complex, their location in the oocytes and their exocytosis upon activation, G's seem to correspond to the typical cortical granules of Anurans. However, they appear to have a macromolecular content different from that of the cortical granules.

A stabilizing interaction between the founder effect and interdeme mixing in competing populations of Drosophila melanogaster and Drosophila simulans

1972 ◽  
Vol 50 (3) ◽  
pp. 325-331 ◽  
Author(s):  
David L. Gibo
Keyword(s):  
Drosophila Melanogaster ◽  
Founder Effect ◽  
Large Population ◽  
Small Population ◽  
Large Populations ◽  
High Predation ◽  
Low Levels ◽  
Relationship Of ◽  
The Relationship ◽  
High Predation Pressure

Population cages with Drosophila melanogaster and D. simulans in competition were maintained under high predation pressure. The cages were established under three different conditions. One group of cages was started with a large population (150 adults) of each species. In these cages D. melanogaster was quickly depressed to low levels by D. simulans. A second group of cages was established with a small population (15 adults) of each species. These cages showed a great deal of diversity of both population size and dominant species. The third group of cages was established by mixing the populations of the cages of the second group and redistributing this mixed population among separate cages. In this last group of cages, the D. simulans population resembled those observed in the cages started with large populations, but the D. melanogaster populations had changed. Instead of being depressed to extinction, D. melanogaster was observed to maintain an apparently stable population. Interspecific competition between the two species appeared to have been reduced. The relationship of these results to the founder effect, interdeme mixing, and rapid changes in competitive relationships is discussed.

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