scholarly journals Growth patterns in brooding dinosaurs reveals the timing of sexual maturity in non-avian dinosaurs and genesis of the avian condition

2007 ◽  
Vol 3 (5) ◽  
pp. 558-561 ◽  
Author(s):  
Gregory M Erickson ◽  
Kristina Curry Rogers ◽  
David J Varricchio ◽  
Mark A Norell ◽  
Xing Xu
Keyword(s):  
Sexual Maturation ◽  
Sexual Maturity ◽  
Reproductive Activity ◽  
Growth Patterns ◽  
The Other ◽  
Growth Line ◽  
Adult Size ◽  
Secondary Sexual Characteristics ◽  
Sexual Characteristics ◽  
Population Sizes

The timing of sexual maturation in non-avian dinosaurs is not known. In extant squamates and crocodilians it occurs in conjunction with the initial slowing of growth rates as adult size is approached. In birds (living dinosaurs) on the other hand, reproductive activity begins well after somatic maturity. Here we used growth line counts and spacing in all of the known brooding non-avian dinosaurs to determine the stages of development when they perished. It was revealed that sexual maturation occurred well before full adult size was reached—the primitive reptilian condition. In this sense, the life history and physiology of non-avian dinosaurs was not like that of modern birds. Palaeobiological ramifications of these findings include the potential to deduce reproductive lifespan, fecundity and reproductive population sizes in non-avian dinosaurs, as well as aid in the identification of secondary sexual characteristics.

scholarly journals Obesity accelerates secondary sexual maturity in girls

2012 ◽  
Vol 52 (4) ◽  
pp. 213
Author(s):  
Meirina Sari ◽  
Endy Paryanto Prawirohartono ◽  
Madarina Julia
Keyword(s):  
Health Effects ◽  
Sexual Maturation ◽  
Sexual Maturity ◽  
Tanner Stage ◽  
Pubic Hair ◽  
Stage Ii ◽  
Secondary Sexual Characteristics ◽  
Hazard Ratios ◽  
Sexual Characteristics ◽  
Secondary Sexual

Background Worldwide incidence of obesity in children isincreasing. Obesity may have many health effects includingadvancement of sexual maturity.Objective T he aim of this study was to assess the timing ofsecondary sexual maturation in obese vs. non􀁄obese girls.Methods Subjects were 105 obese and 105 non􀁄obese girls, aged7 to 8 years who had not entered puberty. Breast and pubic hairgrowth, secondary sexual characteristics, were assessed at baselineand every 4 months for two years. Onset of puberty was defined asTanner stage for secondary sexual maturation of 2: breast Tannerstage II (B2) and/or 2: pubic hair Tanner stage II (P2). Survivalanalyses were used to estimate time to puberty in both groups.Cox regressions were used to analyze possible factors affectingsecondary sexual maturation.Results Mean onset of breast budding (B2) was 7.8 (95% CI 7.7to 7.8) years in obese girls vs. 8.6 (95% CI 8.5 to 8.6) years innon􀁄obese girls (P<O.OOl). Mean onset of pub arc he (P2) was 8.7(95% CI 8.6 to 8.8) years in obese girls vs. 9.0 (95% CI 8.9 to 9.0)years in non􀁄obese girls (P<O.OOl). Hazard ratios of obese girlsto experience an earlier secondary sexual maturation at maturitylevel B2, B3 and P2 were 1.34 (95% CI 1.19 to 1.52), 6.91 (95%CI 3.90 to 12.24) and 3.78 (95% CI 2.42 to 5.89), respectively.Conclusions Obesity was associated with earlier onset ofpuberty in girls. Obese girls entered puberty approximately 3 to9 months earlier than their non􀁄obese peers. [Paediatr Indones.2012;52:213-8].

scholarly journals Growth patterns, sexual dimorphism, and maturation modeled in Pachypleurosauria from Middle Triassic of central Europe (Diapsida: Sauropterygia)

Fossil Record ◽  
2018 ◽  
Vol 21 (1) ◽  
pp. 137-157 ◽  
Author(s):  
Nicole Klein ◽  
Eva Maria Griebeler
Keyword(s):  
Sexual Dimorphism ◽  
Bone Tissue ◽  
Sexual Maturation ◽  
Growth Curves ◽  
Growth Patterns ◽  
The Other ◽  
Tissue Type ◽  
Published Data ◽  
Adult Size ◽  
Germanic Basin

Abstract. Bone tissue, microanatomy, and growth are studied in humeri of the pachypleurosaurs Dactylosaurus from the early Anisian of Poland and of aff. Neusticosaurus pusillus from the Lettenkeuper (early Ladinian) of southern Germany. Histology and modeled growth curves are compared to already published data of other pachypleurosaurs. Therefore, we herein established growth curves for Anarosaurus from the middle Anisian of Winterswijk (the Netherlands) and for pachypleurosaurs from the Anisian/Ladinian of the Alpine Triassic (i.e., Neusticosaurus spp. and Serpianosaurus). Humeri of Dactylosaurus, Anarosaurus, and aff. N. pusillus, all from the Germanic Basin, usually display an inner ring of (pre-)hatchling bone tissue. In some samples this tissue is surrounded by a layer of perpendicularly oriented fine fibers, which could indicate the start of active locomotion for foraging or might be related to viviparity. However, pachypleurosaurs from the Alpine Triassic do not show this tissue. This in turn could be related to overall differences in the environments inhabited (Germanic Basin vs. Alpine Triassic). Histological comparison revealed distinct taxon-specific differences in microanatomy and bone tissue type between Anarosaurus on the one hand and Dactylosaurus and the Neusticosaurus–Serpianosaurus clade on the other hand. Microanatomical differences imply a different degree in secondary adaptation to an aquatic environment. Life-history traits derived histologically and obtained from modeling growth were in general rather similar for all studied pachypleurosaurs. Onset of sexual maturation was within the first third of life. Asymptotic ages (maximum life span) considerably exceeded documented and modeled ages at death in all pachypleurosaur taxa. All traits modeled (more or less) matched values seen in similar-sized extant reptiles. Growth curves revealed differences in growth and maturation strategies within taxa that could indicate sexual dimorphism expressed in different adult sizes and a different onset of sexual maturation. Differences in gender size and morphology is well documented for the Chinese pachypleurosaur Keichousaurus and for Neusticosaurus spp. from the Alpine Triassic. Birth-to-adult size ratios of herein studied pachypleurosaurs were consistent with those seen in other viviparous Sauropterygia, other viviparous extinct taxa as well as extant viviparous reptiles. Anarosaurus had the highest maximum growth rates of all pachypleurosaurs studied, which best conformed to those seen in today's similar-sized reptiles and is expected from its bone tissue type. The other pachypleurosaur taxa had lower rates than the average seen in similar-sized extant reptiles. We hypothesize from our data that the considerably higher asymptotic ages compared to ages at death, early onset of maturation compared to asymptotic age, and viviparity reflect that pachypleurosaurs lived in predator-dominated environments.

Surgical gonadectomy of salmonid fish and subsequent prevention of diseases associated with sexual maturation

1982 ◽  
Vol 81 (3) ◽  
pp. 211-219
Author(s):  
Lydia A. Brown
Keyword(s):  
Sexual Maturation ◽  
Testicular Tissue ◽  
Salmonid Fish ◽  
Practical Solution ◽  
Secondary Sexual Characteristics ◽  
Sexual Characteristics ◽  
Secondary Sexual

SynopsisThe development of various secondary sexual characteristics in salmonids is described, together with a method of preventing sexual maturation by surgical gonadectomy. The major problem in the application of this technique is the regeneration of male testicular tissue, and it is suggested that the practical solution is the use of hormonal feminisation techniques prior to gonadectomy.

scholarly journals Diet and food consumption of the pearl cichlid Geophagus brasiliensis (Teleostei: Cichlidae): relationships with gender and sexual maturity

2011 ◽  
Vol 9 (4) ◽  
pp. 825-830 ◽  
Author(s):  
Rodrigo F. Bastos ◽  
Mário V. Condini ◽  
Antonio S. Varela Junior ◽  
Alexandre M. Garcia
Keyword(s):  
Food Consumption ◽  
Vascular Plants ◽  
Sexual Maturity ◽  
Wide Distribution ◽  
Mean Values ◽  
Secondary Sexual Characteristics ◽  
Geophagus Brasiliensis ◽  
Sexual Characteristics ◽  
Gender Based ◽  
Fish Trade

Despite the importance of the pearl cichlid Geophagus brasiliensis for the aquarium fish trade worldwide and its wide distribution, many aspects of its biology, such as the relationships between its feeding ecology and reproductive behavior, are not fully understood in natural conditions on its native habitat. In this paper, we investigated its diet focusing on how differences in diet and food consumption are related to differences in gender and sexual maturity. The digestive tract of each individual was dissected and had its content analyzed, whereas each gonad was microscopically analyzed to determine gender (male/female) and sexual maturity (immature/mature). A total of 28 females and 31 males were analyzed. Mature individuals were more common than immature specimens both for males (64.50%) and females (64.30%). The analysis of 52 individuals with non-empty digestive tracts revealed a diet comprised of 27 items. According to the Index of Alimentary importance (%IAi), the most important food items in the diet were Gastropoda (37.30%), fragments of vascular plants (15.16%), detritus (10.14%), Amphipoda (9.24%), and fish scales (6.29%). Mature males had more empty stomachs (65.00%) when compared to immature males (27.27%) and immature (55.56%) and mature females (40.00%). Also, mature females seemed to have more food consumption (greater mean values of total volume) in their digestive tracts than mature males. Some hypotheses are proposed in order to distinguish if this gender-based difference in food consumption in mature individuals of the pearl cichlid could be associated with the development of primary and secondary sexual characteristics or with asymmetrical time invested in parental care activities.

Sex determination and Y chromosome constitutive heterochromatin

2019 ◽  
Vol 1 (1) ◽  
pp. 1-5
Author(s):  
Abyt Ibraimov
Keyword(s):  
Sex Determination ◽  
Y Chromosome ◽  
Constitutive Heterochromatin ◽  
Sex Differentiation ◽  
Secondary Sexual Characteristics ◽  
Biological Meaning ◽  
Heterochromatin Block ◽  
Sexual Characteristics ◽  
Open Question ◽  
Efficient Elimination

In many animals, including us, the genetic sex is determined at fertilization by sex chromosomes. Seemingly, the sex determination (SD) in human and animals is determined by the amount of constitutive heterochromatin on Y chromosome via cell thermoregulation. It is assumed the medulla and cortex tissue cells in the undifferentiated embryonic gonads (UEG) differ in vulnerability to the increase of the intracellular temperature. If the amount of the Y chromosome constitutive heterochromatin is enough for efficient elimination of heat difference between the nucleus and cytoplasm in rapidly growing UEG cells the medulla tissue survives. Otherwise it doomed to degeneration and a cortex tissue will remain in the UEG. Regardless of whether our assumption is true or not, it remains an open question why on Y chromosome there is a large constitutive heterochromatin block? What is its biological meaning? Does it relate to sex determination, sex differentiation and development of secondary sexual characteristics? If so, what is its mechanism: chemical or physical? There is no scientifically sound answer to these questions.

Capture of conspecific planktonic larvae by the suspension-feeding gastropod Crepipatella peruviana: association between adult and larval size

2021 ◽  
Vol 87 (1) ◽  
Author(s):  
G A Rivera-Figueroa ◽  
J A Büchner-Miranda ◽  
L P Salas-Yanquin ◽  
J A Montory ◽  
V M Cubillos ◽  
...  
Keyword(s):  
Laboratory Experiments ◽  
Larval Mortality ◽  
Feeding Preference ◽  
The Other ◽  
Suspension Feeding ◽  
Adult Size ◽  
Free Living ◽  
Larval Size ◽  
Suspension Feeders ◽  
Planktonic Larvae

ABSTRACT Free-living, planktonic larvae can be vulnerable to capture and ingestion by adult suspension-feeders. This is particularly the case for larvae that settle gregariously in benthic environments where suspension-feeders occur at high densities. Larvae of gregarious suspension-feeding species are at particularly high risk, as adults of their own species often serve as cues for metamorphosis. We conducted laboratory experiments to assess the extent to which adults of the suspension-feeding caenogastropod Crepipatella peruviana would capture and ingest their own larvae. Experiments were conducted with adults of different sizes, with larvae of different ages and sizes, and in the presence or absence of phytoplankton. Adults captured larvae in all experiments. The presence of microalgae in the water did not influence the extent of larval capture. On average, 39% of larvae were captured during the 3-h feeding periods, regardless of adult size. However, up to 34% of the larvae that were captured on the gill were later discarded as pseudofaeces; the other 64% were ingested. The extent of capture by adults was not related to adult size, or to larval size and, thus, to larval age. Our results suggest that the filtration of congeneric larvae by adult C. peruviana is a result of accidental capture rather than a deliberate feeding preference. Such ingestion could, however, still be an important source of larval mortality, especially when the advanced larvae of this species are searching for a suitable substrate for metamorphosis.

Reproductive failure of the red shiner (Cyprinella lutrensis) after exposure to an exogenous estrogen

2010 ◽  
Vol 67 (11) ◽  
pp. 1730-1743 ◽  
Author(s):  
Michelle M. McGree ◽  
Dana L. Winkelman ◽  
Nicole  K.M.  Vieira ◽  
Alan  M.  Vajda
Keyword(s):  
Reproductive Success ◽  
Great Plains ◽  
Endocrine Disrupting Chemicals ◽  
Water Control ◽  
Secondary Sexual Characteristics ◽  
Cyprinella Lutrensis ◽  
The Us ◽  
Sexual Characteristics ◽  
Solvent Control ◽  
17Β Estradiol

Endocrine disrupting chemicals (EDCs) have been detected in surface waters worldwide and can lead to developmental and reproductive disruption in exposed fishes. In the US Great Plains, EDCs are impacting streams and rivers and may be causing adverse reproductive effects. To examine how estrogenic EDCs might affect reproductive success of plains fishes, we experimentally exposed male red shiners ( Cyprinella lutrensis ) to exogenous 17β-estradiol. We characterized the effects of estradiol on male gonadal histology and secondary sexual characteristics, determined whether exposure reduced reproductive success, and examined the effects of depuration. Adults were exposed to a mean concentration of 70 ng·L−1 estradiol, a solvent control, or a water control for at least 83 days. Male exposure to estradiol resulted in elevated plasma vitellogenin concentrations, changes in spermatogenesis, reduced mating coloration and tubercles, altered mating behaviors, and reduced reproductive success with no viable progeny produced. Reproductive endpoints improved upon depuration (28 days). Exposure to estradiol had significant adverse effects on red shiners, indicating that wild populations may face developmental and reproductive difficulties if they are chronically exposed to estradiol.

Variation within and between Rivers in Adult Size and Sea Age at Maturity of Anadromous Brown Trout, Salmo trutta

1991 ◽  
Vol 48 (6) ◽  
pp. 1015-1021 ◽  
Author(s):  
Jan Henning L'Abée-Lund
Keyword(s):  
Brown Trout ◽  
Sexual Maturity ◽  
Salmo Trutta ◽  
Adult Size ◽  
Age At Maturity ◽  
Migration Distance ◽  
Spawning Area ◽  
Brown Trout Salmo Trutta ◽  
Males And Females ◽  
The Mean

I compared adult size and sea age at sexual maturity among nine populations of anadromous brown trout, Salmo trutta, in two Norwegian rivers to determine the extent of inter- and intrariverine variations. Variation in the mean length of spawners and in the mean sea age at sexual maturity were mainly dependent on the variations found within rather than between rivers. Mean lengths and mean age at maturity of males increased significantly with increasing altitude of the spawning area and with migration distance in freshwater. In females, positive significant correlations were found with mean lengths and altitude of the spawning area and with mean sea age at maturity and both spawning site altitude and migration distance. Mean lengths and ages of males and females were not significantly correlated with the rate of water discharge in the streams during spawning. The size of gravel substrate for spawning was of minor importance in explaining interpopulation variation in mean female size. The increase noted in mean length and in mean sea age at maturity of both males and females is probably an adaptation to greater energy expenditure to reach the uppermost natal spawning areas.

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