scholarly journals Evolutionary conservation and modulation of a juvenile growth-regulating genetic program

2014 ◽  
Vol 52 (3) ◽  
pp. 269-277 ◽  
Author(s):  
Angela Delaney ◽  
Vasantha Padmanabhan ◽  
Geoffrey Rezvani ◽  
Weiping Chen ◽  
Patricia Forcinito ◽  
...  
Keyword(s):  
Body Size ◽  
Time Course ◽  
Mammalian Species ◽  
Genetic Program ◽  
Body Growth ◽  
Striking Similarity ◽  
Large Set ◽  
Adult Size ◽  
Large Mammals ◽  
Multiple Organs

Body size varies enormously among mammalian species. In small mammals, body growth is typically suppressed rapidly, within weeks, whereas in large mammals, growth is suppressed slowly, over years, allowing for a greater adult size. We recently reported evidence that body growth suppression in rodents is caused in part by a juvenile genetic program that occurs in multiple tissues simultaneously and involves the downregulation of a large set of growth-promoting genes. We hypothesized that this genetic program is conserved in large mammals but that its time course is evolutionarily modulated such that it plays out more slowly, allowing for more prolonged growth. Consistent with this hypothesis, using expression microarray analysis, we identified a set of genes that are downregulated with age in both juvenile sheep kidney and lung. This overlapping gene set was enriched for genes involved in cell proliferation and growth and showed striking similarity to a set of genes downregulated with age in multiple organs of the juvenile mouse and rat, indicating that the multiorgan juvenile genetic program previously described in rodents has been conserved in the 80 million years since sheep and rodents diverged in evolution. Using microarray and real-time PCR, we found that the pace of this program was most rapid in mice, more gradual in rats, and most gradual in sheep. These findings support the hypothesis that a growth-regulating genetic program is conserved among mammalian species but that its pace is modulated to allow more prolonged growth and therefore greater adult body size in larger mammals.

scholarly journals Age of maturation and behavioral tactics in male yellow ground squirrel Spermophilus fulvus during mating season

2014 ◽  
Vol 60 (6) ◽  
pp. 700-711 ◽  
Author(s):  
Nina A. Vasilieva ◽  
Ekaterina V. Pavlova ◽  
Sergey V. Naidenko ◽  
Andrey V. Tchabovsky
Keyword(s):  
Body Size ◽  
Ground Squirrel ◽  
Life History Theory ◽  
Social Activity ◽  
Indirect Evidence ◽  
Adult Size ◽  
Adult Males ◽  
Mating Season ◽  
Active Season ◽  
Good Physical Condition

Abstract Life-history theory predicts that in hibernators age of maturation is related positively to body size and negatively to the duration of active season aboveground. Yellow souslik is a large-sized ground squirrel with long hibernation, which suggests late maturation. We used four-year field observations of marked individuals to determine the age of maturation in males through analysis of age-dependent variation in body size, mass, androgen status, timing of spring emergence, ranging patterns and social behavior during the mating season. Yearling males were smaller, lighter, had lower level of fecal testosterone, emerged later and had smaller home ranges than older males. Social activity and the number of females encountered did not differ between age classes. After the second hibernation none of the studied parameters varied with age. Cluster analysis revealed two behavioral tactics: “active” males (adults only) emerged earlier, ranged more widely, initiated more contacts, encountered more females and were heavier than “passive” males (both yearling and adult). Thus, males of S. fulvus reached adult size and matured after two hibernations, which is relatively fast for such a big species with short active period. Indirect evidence for copulations and high variation among yearlings in all parameters suggest that some of them might successfully compete with adults. Active tactic of wandering and searching for females is energetically costly, and probably only adult males in good physical condition can afford it, whereas passive tactic of residing is energy saving and good for adults in poor condition and for yearlings that are continuing to grow.

scholarly journals Role of Mammalian Auditory Cortex in the Perception of Elementary Sound Properties

2001 ◽  
Vol 85 (6) ◽  
pp. 2350-2358 ◽  
Author(s):  
Sanjiv K. Talwar ◽  
Pawel G. Musial ◽  
George L. Gerstein
Keyword(s):  
Auditory Cortex ◽  
Time Course ◽  
Auditory Evoked Potentials ◽  
Mammalian Species ◽  
Sound Intensity ◽  
Primary Auditory Cortex ◽  
Normal Hearing ◽  
Auditory Task ◽  
Experimental Conditions

Studies in several mammalian species have demonstrated that bilateral ablations of the auditory cortex have little effect on simple sound intensity and frequency-based behaviors. In the rat, for example, early experiments have shown that auditory ablations result in virtually no effect on the rat's ability to either detect tones or discriminate frequencies. Such lesion experiments, however, typically examine an animal's performance some time after recovery from ablation surgery. As such, they demonstrate that the cortex is not essential for simple auditory behaviors in the long run. Our study further explores the role of cortex in basic auditory perception by examining whether the cortex is normally involved in these behaviors. In these experiments we reversibly inactivated the rat primary auditory cortex (AI) using the GABA agonist muscimol, while the animals performed a simple auditory task. At the same time we monitored the rat's auditory activity by recording auditory evoked potentials (AEP) from the cortical surface. In contrast to lesion studies, the rapid time course of these experimental conditions preclude reorganization of the auditory system that might otherwise compensate for the loss of cortical processing. Soon after bilateral muscimol application to their AI region, our rats exhibited an acute and profound inability to detect tones. After a few hours this state was followed by a gradual recovery of normal hearing, first of tone detection and, much later, of the ability to discriminate frequencies. Surface muscimol application, at the same time, drastically altered the normal rat AEP. Some of the normal AEP components vanished nearly instantaneously to unveil an underlying waveform, whose size was related to the severity of accompanying behavioral deficits. These results strongly suggest that the cortex is directly involved in basic acoustic processing. Along with observations from accompanying multiunit experiments that related the AEP to AI neuronal activity, our results suggest that a critical amount of activity in the auditory cortex is necessary for normal hearing. It is likely that the involvement of the cortex in simple auditory perceptions has hitherto not been clearly understood because of underlying recovery processes that, in the long-term, safeguard fundamental auditory abilities after cortical injury.

scholarly journals An Extensive Genetic Program Occurring during Postnatal Growth in Multiple Tissues

Endocrinology ◽  
2008 ◽  
Vol 150 (4) ◽  
pp. 1791-1800 ◽  
Author(s):  
Gabriela P. Finkielstain ◽  
Patricia Forcinito ◽  
Julian C. K. Lui ◽  
Kevin M. Barnes ◽  
Rose Marino ◽  
...  
Keyword(s):  
Gene Expression ◽  
Gene Expression Pattern ◽  
Somatic Growth ◽  
Postnatal Growth ◽  
Genetic Program ◽  
Male Rats ◽  
Postnatal Life ◽  
Multiple Organs ◽  
Organ Specific ◽  
Parenchymal Cells

Mammalian somatic growth is rapid in early postnatal life but then slows and eventually ceases in multiple tissues. We hypothesized that there exists a postnatal gene expression program that is common to multiple tissues and is responsible for this coordinate growth deceleration. Consistent with this hypothesis, microarray analysis identified more than 1600 genes that were regulated with age (1 vs. 4 wk) coordinately in kidney, lung, and heart of male mice, including many genes that regulate proliferation. As examples, we focused on three growth-promoting genes, Igf2, Mest, and Peg3, that were markedly down-regulated with age. In situ hybridization revealed that expression occurred in organ-specific parenchymal cells and suggested that the decreasing expression with age was due primarily to decreased expression per cell rather than a decreased number of expressing cells. The declining expression of these genes was slowed during hypothyroidism and growth inhibition (induced by propylthiouracil at 0–5 wk of age) in male rats, suggesting that the normal decline in expression is driven by growth rather than by age per se. We conclude that there exists an extensive genetic program occurring during postnatal life. Many of the involved genes are regulated coordinately in multiple organs, including many genes that regulate cell proliferation. At least some of these are themselves apparently regulated by growth, suggesting that, in the embryo, a gene expression pattern is established that allows for rapid somatic growth of multiple tissues, but then, during postnatal life, this growth leads to negative-feedback changes in gene expression that in turn slow and eventually halt somatic growth, thus imposing a fundamental limit on adult body size.

Cardiac Sarcoidosis: Cytokine Patterns in the Course of the Disease

2003 ◽  
Vol 127 (9) ◽  
pp. 1207-1210 ◽  
Author(s):  
Michael Schoppet ◽  
Sabine Pankuweit ◽  
Bernhard Maisch
Keyword(s):  
Time Course ◽  
Mononuclear Cells ◽  
Cardiac Sarcoidosis ◽  
Systemic Disease ◽  
Healing Process ◽  
Unknown Etiology ◽  
Enzyme Linked Immunosorbent Assay ◽  
Rapid Decline ◽  
Peripheral Blood Mononuclear ◽  
Multiple Organs

Abstract Sarcoidosis is a chronic systemic disease of unknown etiology, which is characterized by noncaseating epitheloid granulomas usually in multiple organs. Here we describe changes in cytokine mRNA expression by peripheral blood mononuclear cells (PBMCs) and changes of cytokine protein levels in plasma over a time course of 12 months in a patient with sarcoidosis confined to the heart as diagnosed by endomyocardial biopsy. Mitogen-stimulated PBMCs exhibited a more TH1 cytokine profile at onset of symptoms before immunosuppressive therapy was initiated, with a change to a TH0 response in the course of the disease as evidenced by multiplex-polymerase chain reaction. In plasma, high levels of interleukin-6 could be detected by an enzyme-linked immunosorbent assay system, with rapid decline correlating with immunosuppression and improving clinical course. These changes may point to a role of TH1 and TH2 cytokines in the pathogenesis and the healing process of cardiac sarcoidosis.

Effects of initial (larval) size and host body temperature on growth in trematodes

2003 ◽  
Vol 81 (4) ◽  
pp. 574-581 ◽  
Author(s):  
Robert Poulin ◽  
A David M. Latham
Keyword(s):  
Body Size ◽  
Body Temperature ◽  
Adult Stage ◽  
Species Variation ◽  
Adult Size ◽  
Model Group ◽  
Larval Size ◽  
Relative Growth ◽  
Host Body ◽  
Adult Body

For ectotherms, temperature is an important correlate of variation in body size within species. Variation in body size among related species could also be attributable in part to temperature if the different species grow under different thermal regimes. The roles of both initial (larval) size and host body temperature on final (adult) size of parasitic trematodes were investigated in a comparative analysis. Trematodes are a good model group for such a study, with almost half of known species growing at high and constant temperatures in endothermic vertebrates and the rest at lower and fluctuating temperatures in ectothermic vertebrates. The relative growth of trematodes, i.e., their growth relative to the size of their larvae, varied greatly among species. Increases in body size from the cercarial larval stage to the adult stage averaged almost 40-fold (maximum 1300-fold), whereas increases in size from the metacercarial stage to the adult stage averaged 6-fold (maximum 110-fold). There were no differences between trematodes in ectothermic hosts and trematodes in endothermic hosts with respect to these measures of relative growth, however, which suggests that host type and the thermal regime provided by the host have no effect on the growth of trematodes from larval to adult stages. In contrast, the final (adult) body size of trematodes appears to be determined to some extent by their initial (larval) size, independently of the type of host in which they developed.

Morphology of cells in the ganglion cell layer during development of the rat retina

1980 ◽  
Vol 208 (1173) ◽  
pp. 433-446 ◽  
Keyword(s):  
Ganglion Cell ◽  
Time Course ◽  
Ganglion Cell Layer ◽  
Ganglion Cells ◽  
Cell Layer ◽  
Type I ◽  
Adult Size ◽  
Rat Retina ◽  
Adult Rat ◽  
Dendritic Fields

The development of the cells in the ganglion cell layer in the rat retina has been studied from 3 to 30 days of age postnatal by means of Golgi-stained whole-mounted retinae. The retina grows rapidly from birth to ten days of age and then more slowly from 10 to 30 days of age. The different classes of ganglion cell can be clearly recognized by 10 days of age, but type I ganglion cells with a size comparable to those found in the adult rat retina are not seen until thirty days of age. Type II cells may attain their adult size before type I cells do. The growth of the retina and the resulting decrease in cell density in the ganglion cell layer occur with the same time course as the increase in the size of the cell soma and their dendritic fields.

New smallest specimen of the pterosaurPteranodonand ontogenetic niches in pterosaurs

2017 ◽  
Vol 92 (2) ◽  
pp. 254-271 ◽  
Author(s):  
S. Christopher Bennett
Keyword(s):  
Body Size ◽  
Parental Care ◽  
Large Body ◽  
Taxonomic Diversity ◽  
Ecological Niches ◽  
Adult Size ◽  
Niobrara Formation ◽  
Large Body Size ◽  
Juvenile Specimen

AbstractA new juvenile specimen ofPteranodonfrom the Smoky Hill Chalk Member of the Niobrara Formation of western Kansas had an estimated wingspan in life of 1.76 m, ~45% smaller than the smallest previously known specimens, but does not differ in morphology from larger specimens. Its presence indicates that juveniles were capable of flying long distances, so it falsifies the interpretation ofPteranodonas growing rapidly to adult size under parental care before flying. Instead juveniles were precocial, growing more slowly to adult size while flying and feeding independently for several years before going to sea. Because juveniles are otherwise unknown in the Smoky Hill Chalk Member, they must have occupied different environments and ecological niches than adults; thusPteranodonexhibited ontogenetic niches. Evidence is presented that most other pterosaurs (e.g.,Rhamphorhynchus,Pterodactylus,Anhanguera) also exhibited various ontogenetic niches, which, along with their large body size, suggests that pterosaur taxonomic diversity was rather low, like that of crocodilians.

scholarly journals Exploring the Role of Insulin Signaling in Relative Growth: A Case Study on Wing-Body Scaling in Lepidoptera

2019 ◽  
Vol 59 (5) ◽  
pp. 1324-1337 ◽  
Author(s):  
Kenneth Z McKenna ◽  
Della Tao ◽  
H Frederik Nijhout
Keyword(s):  
Body Size ◽  
Insulin Signaling ◽  
The Body ◽  
Adult Size ◽  
Tor Signaling ◽  
Relative Growth ◽  
Laboratory Populations ◽  
Body Sizes ◽  
Specific Variation ◽  
Wing Growth

Abstract Adult forms emerge from the relative growth of the body and its parts. Each appendage and organ has a unique pattern of growth that influences the size and shape it attains. This produces adult size relationships referred to as static allometries, which have received a great amount of attention in evolutionary and developmental biology. However, many questions remain unanswered, for example: What sorts of developmental processes coordinate growth? And how do these processes change given variation in body size? It has become increasingly clear that nutrition is one of the strongest influences on size relationships. In insects, nutrition acts via insulin/TOR signaling to facilitate inter- and intra-specific variation in body size and appendage size. Yet, the mechanism by which insulin signaling influences the scaling of growth remains unclear. Here we will discuss the potential roles of insulin signaling in wing-body scaling in Lepidoptera. We analyzed the growth of wings in animals reared on different diet qualities that induce a range of body sizes not normally present in our laboratory populations. By growing wings in tissue culture, we survey how perturbation and stimulation of insulin/TOR signaling influences wing growth. To conclude, we will discuss the implications of our findings for the development and evolution of organismal form.

scholarly journals Medium- and large-sized mammal composition in the Chapada dos Veadeiros National Park and adjacent areas, state of Goiás, Brazil

2019 ◽  
Vol 59 ◽  
pp. e20195942 ◽  
Author(s):  
Átilla Colombo Ferreguetti ◽  
Isadora Cristina Motta Lessa ◽  
Emerson Monteiro Vieira ◽  
André Almeida Cunha ◽  
Helena Godoy Bergallo
Keyword(s):  
Species Composition ◽  
National Park ◽  
Mammalian Species ◽  
Scaling Analysis ◽  
Large Mammals ◽  
Conservation Units ◽  
Mammal Species ◽  
The Difference ◽  
Dry And Rainy Seasons

The Cerrado is the second largest Brazilian biome and only 2.8% is represented by protected areas. Considering the relevance of the Cerrado and Conservation Units in preserving the mammalian diversity, we provided the first assessment of the diversity of medium- and large-sized mammal species in the Chapada dos Veadeiros National Park (CVNP) and surroundings. We tested the effectiveness of the CVNP by assessing the difference in species composition within the park and its surroundings. We sampled CVNP in the rainy (October-December 2013) and dry seasons (March-June 2014) in order to characterize the seasonality within the community. We selected 36 sampling sites to evaluate the composition of the medium and large mammals in the CVNP and its surroundings, 18 in the CVNP and 18 in the park surroundings. We ordered mammalian composition and frequency of individuals data by using a Non-metric Multidimensional Scaling analysis (NMDS). We assessed the effect of season (dry and rainy seasons) and locality (within the CVNP and surroundings) on mammalian species richness with a two-way analysis of variance (Two-way ANOVA). We recorded 23 species, 13 within the CVNP and 17 species in its surroundings. Composition and frequency of records differed between dry and rainy seasons, with higher richness in the rainy season. Species’ composition and the frequency of records were also different between within the CVNP and its surroundings, with higher richness in the surroundings. These results provide information for the increase of the knowledge of mammalian ecology but also is useful as a tool for future strategies to the conservation of these species. More attention should be given to the monitoring of these species in the long term because this area still harbor some viable populations.

History, Distribution, and Conservation, of Large Mammals and Their Habitats in Jordan

1991 ◽  
Vol 18 (1) ◽  
pp. 19-32 ◽  
Author(s):  
Alia Hatough-Bouran ◽  
Ahmad M. Disi
Keyword(s):  
Present Status ◽  
Negative Impact ◽  
Mammalian Species ◽  
Habitat Destruction ◽  
Conservation Strategy ◽  
Rapid Decline ◽  
Large Mammals ◽  
The Past ◽  
Sequence Of Events ◽  
Natural Pasture

Jordan lies at a meeting-point of three zoogeographical areas: the Palaearctic, the Afrotropical, and the Oriental—circumstances which were conducive to habitat diversity in Jordan and hence the diversity and often abundant occurrence of different floral and faunal elements.The present paper gives information about the history and past occurrence of large mammalian species and their populations in Jordan, while also focusing on the present status of the large mammalian species, and gives the reasons for extinctions and the preventive measures that are being taken to conserve the populations remaining. In addition, this study gives a future prospective outlook for habitat and mammalian conservation, and the reintroduction programme that is being implemented in Jordan.The first part of the paper sheds light on the past existence of large mammals in Jordan. The historical sequence of events starting from the Upper Palaeolithic and continuing right up to the present, and the succession of civilizations, had a negative impact on the large mammalian populations. This section gives tabulated data on the past occurrence of 26 species, supported by evidence of their past existence such as bone remains, rock drawings, engravings, mosaics, and frescos, found in various archaeological sites in Jordan.The second part of the paper deals with the present status of large mammalian populations, their distribution being reflected through maps indicating recent sightings in some outstanding cases. Among those are reintroduced species such as the Arabian Oryx and the Syrian Wild Ass, and highly threatened species such as the Nubian Ibex. This part also investigates the reasons for extinction, which mainly link the destruction of habitats with the direct deterioration of mammalian populations. Habitat destruction was chiefly due to the rapid decline of the natural pasture areas, overgrazing, urban expansions, unorganized construction plans, human impact, mismanagement of the highlands, fire, and hunting. All of these factors led to deforestation and soil erosion, resulting in a patchy, fragile ecocomplex. The decrease of rainfall assisted the severe deterioration of natural forests.The future outlook of this study includes plans to restore ecosystems and, with them, much of the overall ecocomplex. For this and other reasons it also stresses the urgent need to establish more reserves, both grazing and natural. This concluding part of the paper encourages the improvement of national parks, and urges the authorities to look seriously at the often disastrous effects of mismanagement. The importance of collaboration between Jordan and the various international agencies is emphasized, as well as the need to speed up work on the National Conservation Strategy of Jordan.

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