scholarly journals Genomic evidence for the parallel regression of melatonin synthesis and signaling pathways in placental mammals

2021 ◽  
Vol 1 ◽  
pp. 75
Author(s):  
Christopher A. Emerling ◽  
Mark S. Springer ◽  
John Gatesy ◽  
Zachary Jones ◽  
Deana Hamilton ◽  
...  
Keyword(s):  
Pineal Gland ◽  
Selection Pressure ◽  
Complete Loss ◽  
Molecular Signatures ◽  
Vertebrate Species ◽  
Relaxed Selection ◽  
Selective Pressures ◽  
Melatonin Synthesis ◽  
Subterranean Mammals ◽  
Inactivating Mutations

Background: The study of regressive evolution has yielded a wealth of examples where the underlying genes bear molecular signatures of trait degradation, such as pseudogenization or deletion. Typically, it appears that such disrupted genes are limited to the function of the regressed trait, whereas pleiotropic genes tend to be maintained by natural selection to support their myriad purposes. One such set of genes is involved in the synthesis (AANAT, ASMT) and signaling (MTNR1A, MTNR1B) of melatonin, a hormone secreted by the vertebrate pineal gland. Melatonin provides a signal of environmental darkness, thereby influencing the circadian and circannual rhythmicity of numerous physiological traits. Therefore, the complete loss of a pineal gland and the underlying melatonin pathway genes seems likely to be maladaptive, unless compensated by extrapineal sources of melatonin. Methods: We examined AANAT, ASMT, MTNR1A and MTNR1B in 123 vertebrate species, including pineal-less placental mammals and crocodylians. We searched for inactivating mutations and modelled selective pressures (dN/dS) to test whether the genes remain functionally intact. Results: We report that crocodylians retain intact melatonin genes and express AANAT and ASMT in their eyes, whereas all four genes have been repeatedly inactivated in the pineal-less xenarthrans, pangolins, sirenians, and whales. Furthermore, colugos have lost these genes, and several lineages of subterranean mammals have partial melatonin pathway dysfunction. These results are supported by the presence of shared inactivating mutations across clades and analyses of selection pressure based on the ratio of non-synonymous to synonymous substitutions (dN/dS), suggesting extended periods of relaxed selection on these genes. Conclusions: The losses of melatonin synthesis and signaling dates to tens of millions of years ago in several lineages of placental mammals, raising questions about the evolutionary resilience of pleiotropic genes, and the causes and consequences of losing melatonin pathways in these species.

scholarly journals Genomic evidence for the parallel regression of melatonin synthesis and signaling pathways in placental mammals

2021 ◽  
Vol 1 ◽  
pp. 75
Author(s):  
Christopher A. Emerling ◽  
Mark S. Springer ◽  
John Gatesy ◽  
Zachary Jones ◽  
Deana Hamilton ◽  
...  
Keyword(s):  
Pineal Gland ◽  
Selection Pressure ◽  
Complete Loss ◽  
Molecular Signatures ◽  
Vertebrate Species ◽  
Relaxed Selection ◽  
Selective Pressures ◽  
Melatonin Synthesis ◽  
Subterranean Mammals ◽  
Inactivating Mutations

Background: The study of regressive evolution has yielded a wealth of examples where the underlying genes bear molecular signatures of trait degradation, such as pseudogenization or deletion. Typically, it appears that such disrupted genes are limited to the function of the regressed trait, whereas pleiotropic genes tend to be maintained by natural selection to support their myriad purposes. One such set of pleiotropic genes is involved in the synthesis (AANAT, ASMT) and signaling (MTNR1A, MTNR1B) of melatonin, a hormone secreted by the vertebrate pineal gland. Melatonin provides a signal of environmental darkness, thereby influencing the circadian and circannual rhythmicity of numerous physiological traits. Therefore, the complete loss of a pineal gland and the underlying melatonin pathway genes seems likely to be maladaptive, unless compensated by extrapineal sources of melatonin. Methods: We examined AANAT, ASMT, MTNR1A and MTNR1B in 123 vertebrate species, including pineal-less placental mammals and crocodylians. We searched for inactivating mutations and modelled selective pressures (dN/dS) to test whether the genes remain functionally intact. Results: We report that crocodylians retain intact melatonin genes and express AANAT and ASMT in their eyes, whereas all four genes have been repeatedly inactivated in the pineal-less xenarthrans, pangolins, sirenians, and whales. Furthermore, colugos have lost these genes, and several lineages of subterranean mammals have partial melatonin pathway dysfunction. These results are supported by the presence of shared inactivating mutations across clades and analyses of selection pressure based on the ratio of non-synonymous to synonymous substitutions (dN/dS), suggesting extended periods of relaxed selection on these genes. Conclusions: The losses of melatonin synthesis and signaling date to tens of millions of years ago in several lineages of placental mammals, raising questions about the evolutionary resilience of pleiotropic genes, and the causes and consequences of losing melatonin pathways in these species.

Monosodium glutamate administration early in life alters pineal melatonin nocturnal profile in adulthood

2021 ◽  
Vol 4 (1) ◽  
pp. 99-114
Author(s):  
Janaína B Garcia ◽  
Fernanda G Do Amaral ◽  
Daniela C Buonfiglio ◽  
Rafaela FA Vendrame ◽  
Patrícia L Alves ◽  
...  
Keyword(s):  
Insulin Resistance ◽  
Body Weight ◽  
Pineal Gland ◽  
Serum Insulin ◽  
Monosodium Glutamate ◽  
Female Rats ◽  
Pineal Melatonin ◽  
Melatonin Synthesis ◽  
Male And Female Rats ◽  
Melatonin Production

The pineal gland synthesizes melatonin exclusively at night, which gives melatonin the characteristic of a temporal synchronizer of the physiological systems. Melatonin is a regulator of insulin activities centrally and also peripherally and its synthesis is reduced in diabetes.  Since monosodium glutamate (MSG) is often used to induce the type 2 diabetic and metabolic syndrome in animal models, the purpose of this work is to evaluate the potential effects of MSG given to neonates on the pineal melatonin synthesis in different aged male and female rats. Wistar rats were subcutaneously injected with MSG (4mg/g/day) or saline solution (0.9%) from the second to eighth post-natal day. The circadian profiles both melatonin levels and AANAT activity were monitored at different ages. Body weight, naso-anal length, adipose tissues weight, GTT, ITT and serum insulin levels were also evaluated. Typical obesity with the neonatal MSG treatment was observed, indicated by a great increase in adipose depots without a concurrent increase in body weight. MSG treatment did not cause hyperglycemia or glucose intolerance, but induced insulin resistance. An increase of melatonin synthesis at ZT 15 with phase advance was observed in in some animals. The AANAT activity was positively parallel to the melatonin circadian profile. It seems that MSG causes hypothalamic obesity which may increase AANAT activity and melatonin production in pineal gland. These effects were not temporally correlated with insulin resistance and hyperinsulinemia indicating the hypothalamic lesions, particularly in arcuate nucleus induced by MSG in early age, as the principal cause of the increase in melatonin production.

scholarly journals Rumen-Protected 5-Hydroxytryptophan Improves Sheep Melatonin Synthesis in the Pineal Gland and Intestinal Tract

2019 ◽  
Vol 25 ◽  
pp. 3605-3616 ◽  
Author(s):  
Fang Zhao ◽  
Chen Ma ◽  
Guodong Zhao ◽  
Gen Wang ◽  
Xiaobin Li ◽  
...  
Keyword(s):  
Pineal Gland ◽  
Intestinal Tract ◽  
Melatonin Synthesis

MicroRNA-7 inhibits melatonin synthesis by acting as a linking molecule between leptin and norepinephrine signaling pathways in pig pineal gland

2019 ◽  
Vol 66 (3) ◽  
pp. e12552 ◽  
Author(s):  
Jingtao Qiu ◽  
Jinglin Zhang ◽  
Yewen Zhou ◽  
Xin Li ◽  
Hongjiao Li ◽  
...  
Keyword(s):  
Pineal Gland ◽  
Signaling Pathways ◽  
Melatonin Synthesis

Avian Melatonin Synthesis: Photic and Circadian Regulation of Serotonin N-Acetyltransferase mRNA in the Chicken Pineal Gland and Retina

2002 ◽  
Vol 68 (1) ◽  
pp. 213-224 ◽  
Author(s):  
Marianne Bernard ◽  
P. Michael Iuvone ◽  
Vincent M. Cassone ◽  
Patrick H. Roseboom ◽  
Steven L. Coon ◽  
...  
Keyword(s):  
Pineal Gland ◽  
Circadian Regulation ◽  
Melatonin Synthesis

scholarly journals aCGH Analysis to Estimate Genetic Variations among Domesticated Chickens

2016 ◽  
Vol 2016 ◽  
pp. 1-8 ◽  
Author(s):  
Tomoyoshi Komiyama ◽  
Mengjie Lin ◽  
Atsushi Ogura
Keyword(s):  
Comparative Genomic Hybridization ◽  
Selection Pressure ◽  
Array Comparative Genomic Hybridization ◽  
Comparative Genomic ◽  
Genomic Hybridization ◽  
Selective Pressures ◽  
Number Of Genes ◽  
Chicken Breeds ◽  
Ancient Times ◽  
Genomic Regions

Chickens have been familiar to humans since ancient times and have been used not only for culinary purposes but also for cultural purposes including ritual ceremonies and traditional entertainment. The various chicken breeds developed for these purposes often display distinct morphological and/or behavioural traits. For example, the JapaneseShamois larger and more aggressive than other domesticated chickens, reflecting its role as a fighting cock breed, whereas JapaneseNaganakidoribreeds, which have long-crowing behaviour, were bred instead for their entertaining and aesthetic qualities. However, the genetic backgrounds of these distinct morphological and behavioural traits remain unclear. Therefore, the question arises as to which genomic regions in these chickens were acted upon by selective pressures through breeding. We compared the entire genomes of six chicken breeds domesticated for various cultural purposes by utilizing array comparative genomic hybridization. From these analyses, we identified 782 regions that underwent insertions, deletions, or mutations, representing man-made selection pressure in these chickens. Furthermore, we found that a number of genes diversified in domesticated chickens bred for cultural or entertainment purposes were different from those diversified in chickens bred for food, such as broilers and layers.

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