DOCSLIB.ORG

34667 U01 UNCORR PRF 1..14

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
34667 U01 UNCORR PRF 1..14 34667_u01_UNCORR_PRF.3d_1_08-27-07 Part I Strategies, Methods and Background ____À1 ____0 ____þ1 34667_u01_UNCORR_PRF.3d_2_08-27-07 1 ____ 0 ____ 1 ____ 34667_u01_UNCORR_PRF.3d_3_08-27-07 Chapter 1 Why Are There Two Sexes? Turk Rhen and David Crews One of the most fascinating aspects of life on earth is underlying sexual differentiation of the body and the myriad of differences between males and females mind should lead to novel therapies designed to pre- (Judson, 2002). Children and adults alike are capti- vent birth defects and cure devastating neurological vated when they first learn that males, rather than diseases. females, gestate and give birth to offspring in certain To fully comprehend sex differences in the brain species of seahorse. Role reversal is also observed in and behavior in humans and to appreciate how ani- the red-necked phalarope, a shorebird in which poly- mals can be used to model these differences, we need androus females are more brightly colored than their to examine sexual dimorphisms in an evolutionary mates and males alone incubate eggs. People are like- context. The basic principle that guides biomedical wise amazed when they hear that ambient tempera- research is that genetic, developmental, physiological, ture determines the sex of many reptiles. While such and behavioral mechanisms are conserved in species unusual phenomena capture our curiosity, there are that have evolved from common ancestors. The unity also practical reasons for studying sex differences. For of life is seen in our hereditary material: the universal instance, defects in development of the reproductive genetic code, the enzymes that synthesize DNA, and tract and genitalia are fairly common in humans. Sex the proteins that distribute chromosomes to daughter differences in physiology and disease affect virtually cells during mitosis and meiosis. This principle also every organ system in the human body, including the permits significant advances in neuroscience. Hodg- nervous system. Depression, Alzheimer’s disease, and kin and Huxley, for example, used the giant axon of schizophrenia are examples of afflictions that differ squid to elucidate action potentials (Clay, 2005). Our in incidence, onset, and/or symptoms between males knowledge of the mechanisms underlying long-term ____À1 and females. Understanding of the mechanisms potentiation and learning has been furthered by studies ____0 ____þ1 3 34667_u01_UNCORR_PRF.3d_4_08-27-07 4 STRATEGIES, METHODS AND BACKGROUND in sea slugs (Kandel, 2004). Research on guinea pigs ultimately drives neural evolution. We bring the has been critical in formation of the concept of or- chapter to a close by briefly outlining what is known ganization and activation of sexual behavior by go- about sexual differentiation of neural mechanisms in nadal steroids (Pheonix et al., 1959). Consequently, humans. These mechanisms are undoubtedly related male seahorses giving birth, polyandrous female phal- to sex differences in aggressive and sexual behavior aropes, and reptiles with temperature-dependent sex and emotional memory, as well as the incidence of determination may not be as esoteric as they seem if affective disorders, anxiety disorders, schizophrenia, conserved genes and biological processes have been and post-traumatic stress disorder (PTSD). co-opted for different uses during evolution. Still, these examples highlight an emerging paradox in studies of sexual differentiation. Reproductive traits in THE EVOLUTION OF EUKARYOTES, general appear to be evolving more rapidly than other MEIOSIS, AND TWO SEXES characteristics. Here we provide a three-part intro- duction to sex differences, stressing both the conserved Advances in molecular and cellular biology, along and the unique as part of Darwin’s notion of descent with comparative genomics, are allowing reconstruc- with modification (Darwin, 1859). tion of the earliest stages in the evolution of life on In the first section, we step back in time and pro- earth. The first organisms lacked a membrane-bound vide a broad perspective on the evolution of eukary- nucleus, replicated by binary fission, and are survived otes. The evolution of meiosis and syngamy (i.e., the by today’s prokaryotes. Two groups of extant prokary- fusion of two cells) was a precondition for the evolu- otes, the eubacteria and the archaebacteria, appear to tion of dimorphic gametes and the subsequent evo- be as distinct from one another as they are from eu- lution of all other sex differences. We then outline karyotes (Brown & Doolittle, 1997; Bell & Jackson, general causes of sex differences in animals by fo- 2001; Forterre, 2001; Makarova & Koonin, 2003; cusing on natural and sexual selection. In particular, Robinson & Bell, 2005). This finding makes it diffi- we illustrate how sex-specific selection can favor dif- cult to codify the prokaryote-eukaryote transition (Mar- ferent phenotypes in males and females. This pattern tin, 2005). Yet, research is beginning to elucidate how of divergent selection ultimately leads to changes in the first nucleated cells originated and diversified. the neural mechanisms that regulate behavior in the Some of the most important events in the evolution of two sexes. eukaryotes involved symbioses (mutually beneficial In the second section, we explain the mechanisms associations of different species). For instance, the that underlie sex differences in gene expression as well endosymbiotic theory for the origin of mitochondria as the basic developmental mechanisms that produce is well established, even if the timing is in dispute sex differences. Despite abundant examples of differ- (Embley & Martin, 2006). ential selection on males versus females, there is an One hypothesis has it that the first eukaryotes inherent constraint to the evolution of sex differences. lacked endosymbionts (currently represented by di- To be precise, the same genes control homologous plomonads, parabasalids, and microsporidia) and that traits in both sexes. We describe how several mecha- endosymbionts were acquired in a separate lineage nisms relieve this genetic constraint. For instance, ge- that gave rise to eukaryotes with mitochondria. An netic differences in the form of sex chromosomes and alternative hypothesis suggests that endosymbiotic sex-linked genes have evolved independently in many bacteria were acquired concurrent (or nearly so) with eukaryotic lineages. Another major mechanism is sex- the origin of eukaryotes and that these organisms limited (or differential) expression of autosomal loci, evolved into mitochondria as well as the more derived as exemplified by hormonal regulation of gene expres- organelles called hydrogenosomes and mitosomes in sion. Environmental factors can also have a large im- eukaryotes that lack prototypical mitochondria (Em- pact on the development of sex differences, a pheno- bley & Martin, 2006). In either case, this ancient menon commonly referred to as phenotypic plasticity. event has direct implications for human health be- Finally, we review some elegant research that links cause mutations in mitochondrial DNA, which is evolutionary causes of and proximate mechanisms for maternally inherited, cause a number of diseases 1 ____ sex differences in the brain and behavior. These ex- (Chen & Butow, 2005; Dimauro & Davidzon, 2005). 0 ____ amples show how sex-specific selection on behavior Mitochondria also play a central role in apoptosis, 1 ____ 34667_u01_UNCORR_PRF.3d_5_08-27-07 WHY ARE THERE TWO SEXES? 5 a form of cell death that contributes to normal de- the centrosome in periventricular cells and are hy- velopment and to diverse pathological states (Schafer pothesized to regulate formation and orientation of & Kornbluth, 2006; Garrido et al., 2006). It is espe- the mitotic spindle. Proliferation of neural progenitors cially interesting that vertebrates evolved the capacity occurs when spindle fibers run parallel to the ven- for a novel class of molecules (i.e., estrogens and an- tricular epithelium. In contrast, neurogenesis gener- drogens) to influence mitochondia-dependent apo- ally occurs when spindle fibers are perpendicular to ptosis in the nervous system (Nilsen & Brinton, 2004; the ventricular epithelium. Exactly how orientation of Forger, 2006; Lin et al., 2006). the mitotic spindle relates to commitment to a neu- There are several hypotheses for the origin of the ronal fate is unknown, but it is possible that the post- membrane-bound nucleus (Martin, 2005), but two mitotic location of the centrosome (i.e., cell asymmetry basic categories can be distinguished. The first group and microtubule polarity) is vital, like it is to devel- of hypotheses suggests direct evolution of this unique opment of neuronal polarity (de Anda et al., 2005). structure in the initial forms of life (Woese, 1998), Again, we see how an ancient event in the evolution of while the second posits a symbiotic origin for the nu- eukaryotes has implications for neural development. cleus (Dolan et al., 2002). Whether the nucleus evol- While mitochondria and mitosis are important to ved de novo or from an archaebacterial-eubacterial human health, the adaptations most salient to our symbiont, it is clear that microtubules played a central discussion of sex differences are meiosis and syngamy. role in the evolution of eukaryotes. Microtubules are Three simple molecular changes account for the essential for mitosis and are a key component of the transition from mitosis to meiosis. The first change cytoskeleton. Moreover, the first split within the eukar- was in alignment
Load more

Recommended publications
  • REVIEW Physiological Dependence on Copulation in Parthenogenetic Females Can Reduce the Cost of Sex
    ANIMAL BEHAVIOUR, 2004, 67, 811e822 doi:10.1016/j.anbehav.2003.05.014 REVIEW Physiological dependence on copulation in parthenogenetic females can reduce the cost of sex M. NEIMAN Department of Biology, Indiana University, Bloomington (Received 6 December 2002; initial acceptance 10 April 2003; final acceptance 27 May 2003; MS. number: ARV-25) Despite the two-fold reproductive advantage of asexual over sexual reproduction, the majority of eukaryotic species are sexual. Why sex is so widespread is still unknown and remains one of the most important unanswered questions in evolutionary biology. Although there are several hypothesized mechanisms for the maintenance of sex, all require assumptions that may limit their applicability. I suggest that the maintenance of sex may be aided by the detrimental retention of ancestral traits related to sexual reproduction in the asexual descendants of sexual taxa. This reasoning is based on the fact that successful reproduction in many obligately sexual species is dependent upon the behavioural, physical and physiological cues that accompany sperm delivery. More specifically, I suggest that although parthenogenetic (asexual) females have no need for sperm per se, parthenogens descended from sexual ancestors may not be able to reach their full reproductive potential in the absence of the various stimuli provided by copulatory behaviour. This mechanism is novel in assuming no intrinsic advantage to producing genetically variable offspring; rather, sex is maintained simply through phylogenetic constraint. I review and synthesize relevant literature and data showing that access to males and copulation increases reproductive output in both sexual and parthenogenetic females. These findings suggest that the current predominance of sexual reproduction, despite its well-documented drawbacks, could in part be due to the retention of physiological dependence on copulatory stimuli in parthenogenetic females.
    [Show full text]
  • Sex-Specific Spawning Behavior and Its Consequences in an External Fertilizer
    vol. 165, no. 6 the american naturalist june 2005 Sex-Specific Spawning Behavior and Its Consequences in an External Fertilizer Don R. Levitan* Department of Biological Science, Florida State University, a very simple way—the timing of gamete release (Levitan Tallahassee, Florida 32306-1100 1998b). This allows for an investigation of how mating behavior can influence mating success without the com- Submitted October 29, 2004; Accepted February 11, 2005; Electronically published April 4, 2005 plications imposed by variation in adult morphological features, interactions within the female reproductive sys- tem, or post-mating (or pollination) investments that can all influence paternal and maternal success (Arnqvist and Rowe 1995; Havens and Delph 1996; Eberhard 1998). It abstract: Identifying the target of sexual selection in externally also provides an avenue for exploring how the evolution fertilizing taxa has been problematic because species in these taxa often lack sexual dimorphism. However, these species often show sex of sexual dimorphism in adult traits may be related to the differences in spawning behavior; males spawn before females. I in- evolutionary transition to internal fertilization. vestigated the consequences of spawning order and time intervals One of the most striking patterns among animals and between male and female spawning in two field experiments. The in particular invertebrate taxa is that, generally, species first involved releasing one female sea urchin’s eggs and one or two that copulate or pseudocopulate exhibit sexual dimor- males’ sperm in discrete puffs from syringes; the second involved phism whereas species that broadcast gametes do not inducing males to spawn at different intervals in situ within a pop- ulation of spawning females.
    [Show full text]
  • The Seahorse Genome and the Evolution of Its Specialized
    OPEN ARTICLE doi:10.1038/nature20595 The seahorse genome and the evolution of its specialized morphology Qiang Lin1*§, Shaohua Fan2†*, Yanhong Zhang1*, Meng Xu3*, Huixian Zhang1,4*, Yulan Yang3*, Alison P. Lee4†, Joost M. Woltering2, Vydianathan Ravi4, Helen M. Gunter2†, Wei Luo1, Zexia Gao5, Zhi Wei Lim4†, Geng Qin1,6, Ralf F. Schneider2, Xin Wang1,6, Peiwen Xiong2, Gang Li1, Kai Wang7, Jiumeng Min3, Chi Zhang3, Ying Qiu8, Jie Bai8, Weiming He3, Chao Bian8, Xinhui Zhang8, Dai Shan3, Hongyue Qu1,6, Ying Sun8, Qiang Gao3, Liangmin Huang1,6, Qiong Shi1,8§, Axel Meyer2§ & Byrappa Venkatesh4,9§ Seahorses have a specialized morphology that includes a toothless tubular mouth, a body covered with bony plates, a male brood pouch, and the absence of caudal and pelvic fins. Here we report the sequencing and de novo assembly of the genome of the tiger tail seahorse, Hippocampus comes. Comparative genomic analysis identifies higher protein and nucleotide evolutionary rates in H. comes compared with other teleost fish genomes. We identified an astacin metalloprotease gene family that has undergone expansion and is highly expressed in the male brood pouch. We also find that the H. comes genome lacks enamel matrix protein-coding proline/glutamine-rich secretory calcium-binding phosphoprotein genes, which might have led to the loss of mineralized teeth. tbx4, a regulator of hindlimb development, is also not found in H. comes genome. Knockout of tbx4 in zebrafish showed a ‘pelvic fin-loss’ phenotype similar to that of seahorses. Members of the teleost family Syngnathidae (seahorses, pipefishes de novo. The H. comes genome assembly is of high quality, as > 99% and seadragons) (Extended Data Fig.
    [Show full text]
  • Revlined Seahorse Dad Copy
    Diligent Dads In the wild animal world, there are a number of nurturing males, including the seahorse The lined seahorse gets its name from its vertical stripes. They can change colors to provide camouflage or denote mood. Photo credit: Linda De Volder By J. Morton Galetto, CU Maurice River When it comes to fathering, the animal world exhibits a spectrum from love ‘em and leave ‘em to champion surveillance. In honor of Father’s Day let’s discuss some superior dads. In the animal kingdom the emperor penguin male takes sole responsibility for incubating an egg. It is balanced on his feet which he shuffles along the ice of Antarctica for two months, enduring 125 mph winds and – 40 temperatures. Hundreds of huddling fathers bear this responsibility while their mates are at sea fattening-up. This story of dedication and endurance is powerful and heart-warming. Emperor penguins’ dedication leads them to be described as the #1 exemplary father in a multitude of articles. I highly recommend the 2005 film “March of the Penguins,” that documents this challenging fatherly devotion. In fact every dead-beat dad should be required to watch “March of the Penguins,” repeatedly, even if it doesn’t help. But our story is not about parental neglect; it is about celebrating great dads. Let’s bring it home a bit, since most of us will never visit Antarctica and certainly not in 125 mph winds. We’ll explore some local creatures and focus on one unexpected twist in fathering. In past articles we have discussed some dutiful parents of the avian variety.
    [Show full text]
  • Courtship Behavior in the Dwarf Seahorse, Hippocampuszosterae
    Copeia, 1996(3), pp. 634-640 Courtship Behavior in the Dwarf Seahorse, Hippocampuszosterae HEATHER D. MASONJONESAND SARA M. LEWIS The seahorse genus Hippocampus (Syngnathidae) exhibits extreme morpho- logical specialization for paternal care, with males incubating eggs within a highly vascularized brood pouch. Dwarf seahorses, H. zosterae, form monoga- mous pairs that court early each morning until copulation takes place. Daily behavioral observations of seahorse pairs (n = 15) were made from the day of introduction through the day of copulation. Four distinct phases of seahorse courtship are marked by prominent behavioral changes, as well as by differences in the intensity of courtship. The first courtship phase occurs for one or two mornings preceding the day of copulation and is characterized by reciprocal quivering, consisting of rapid side-to-side body vibrations displayed alternately by males and females. The remaining courtship phases are restricted to the day of copulation, with the second courtship phase distinguished by females pointing, during which the head is raised upward. In the third courtship phase, males begin to point in response to female pointing. During the final phase of courtship, seahorse pairs repeatedly rise together in the water column, eventually leading to females transferring their eggs directly into the male brood pouch during a brief midwater copulation. Courtship activity level (representing the percentage of time spent in courtship) increased from relatively low levels during the first courtship phase to highly active courtship on the day of copulation. Males more actively initiated courtship on the days preceding copulation, indicating that these seahorses are not courtship-role reversed, as has previously been assumed.
    [Show full text]
  • Marine Protected Species Identification Guide
    Department of Primary Industries and Regional Development Marine protected species identification guide June 2021 Fisheries Occasional Publication No. 129, June 2021. Prepared by K. Travaille and M. Hourston Cover: Hawksbill turtle (Eretmochelys imbricata). Photo: Matthew Pember. Illustrations © R.Swainston/www.anima.net.au Bird images donated by Important disclaimer The Chief Executive Officer of the Department of Primary Industries and Regional Development and the State of Western Australia accept no liability whatsoever by reason of negligence or otherwise arising from the use or release of this information or any part of it. Department of Primary Industries and Regional Development Gordon Stephenson House 140 William Street PERTH WA 6000 Telephone: (08) 6551 4444 Website: dpird.wa.gov.au ABN: 18 951 343 745 ISSN: 1447 - 2058 (Print) ISBN: 978-1-877098-22-2 (Print) ISSN: 2206 - 0928 (Online) ISBN: 978-1-877098-23-9 (Online) Copyright © State of Western Australia (Department of Primary Industries and Regional Development), 2021. ii Marine protected species ID guide Contents About this guide �������������������������������������������������������������������������������������������1 Protected species legislation and international agreements 3 Reporting interactions ���������������������������������������������������������������������������������4 Marine mammals �����������������������������������������������������������������������������������������5 Relative size of cetaceans �������������������������������������������������������������������������5
    [Show full text]
  • Multiple Mating and Its Relationship to Alternative Modes of Gestation in Male-Pregnant Versus Female-Pregnant fish Species
    Multiple mating and its relationship to alternative modes of gestation in male-pregnant versus female-pregnant fish species John C. Avise1 and Jin-Xian Liu Department of Ecology and Evolutionary Biology, University of California, Irvine, CA 92697 Contributed by John C. Avise, September 28, 2010 (sent for review August 20, 2010) We construct a verbal and graphical theory (the “fecundity-limitation within which he must incubate the embryos that he has sired with hypothesis”) about how constraints on the brooding space for em- one or more mates (14–17). This inversion from the familiar bryos probably truncate individual fecundity in male-pregnant and situation in female-pregnant animals apparently has translated in female-pregnant species in ways that should differentially influence some but not all syngnathid species into mating systems char- selection pressures for multiple mating by males or by females. We acterized by “sex-role reversal” (18, 19): a higher intensity of then review the empirical literature on genetically deduced rates of sexual selection on females than on males and an elaboration of fi multiple mating by the embryo-brooding parent in various fish spe- sexual secondary traits mostly in females. For one such pipe sh cies with three alternative categories of pregnancy: internal gesta- species, researchers also have documented that the sexual- tion by males, internal gestation by females, and external gestation selection gradient for females is steeper than that for males (20). More generally, fishes should be excellent subjects for as- (in nests) by males. Multiple mating by the brooding gender was fl common in all three forms of pregnancy.
    [Show full text]
  • THE 7TH ANNUAL May 3, 2019 MAY 3, 2019
    THE 7TH ANNUAL May 3, 2019 MAY 3, 2019 Schedule 2:00 - 3:00 p.m. Keynote Speaker 3:00 - 3:55 p.m. Poster Session I 4:05 - 5:00 p.m. Poster Session II Awards for Best poster presentations will Be announced immediately following the poster sessions. Symposium Organizers: Dr. Eric Freundt, Dr. Simon Schuler, Olivia Crimbly, and Devon Grey. The CNHS Undergraduate Research Symposium provides an opportunity for students within the College of Natural and Health Sciences to present their current or recently completed research projects in a poster format. The research may have been performed as part of a course, an Honors Research Fellowship, or an independent project conducted with a faculty mentor. ABstracts for all poster presentations are included in this booklet and are listed in alphabetical order based on the presenting author’s last name. The Symposium was initiated in 2013 through a generous grant from the UT Board of Fellows. Further financial support from the Office of the Dean of CNHS, the Department of Biology and Department of Chemistry, Biochemistry and Physics is also acknowledged. Finally, the organizers would like to thank all presenters, faculty mentors, and faculty judges for their participation in this event. 1 Keynote Speaker Florida Red Tide: What's new, what's true, and what you should know. Dr. Cynthia Heil Director, Red Tide Institute Mote Marine LaBoratory 2 Poster Session I * Denotes authors presenting at symposium (1) Isolation of Marine Sediment-Derived Bacteria that (8) Does Response of Weekly Strength Training Volume on Produce Biologically Active Metabolites Muscular Hypertrophic Adaptations in Trained GaBriella AlBert*1and Dr.
    [Show full text]
  • Guide to Theecological Systemsof Puerto Rico
    United States Department of Agriculture Guide to the Forest Service Ecological Systems International Institute of Tropical Forestry of Puerto Rico General Technical Report IITF-GTR-35 June 2009 Gary L. Miller and Ariel E. Lugo The Forest Service of the U.S. Department of Agriculture is dedicated to the principle of multiple use management of the Nation’s forest resources for sustained yields of wood, water, forage, wildlife, and recreation. Through forestry research, cooperation with the States and private forest owners, and management of the National Forests and national grasslands, it strives—as directed by Congress—to provide increasingly greater service to a growing Nation. The U.S. Department of Agriculture (USDA) prohibits discrimination in all its programs and activities on the basis of race, color, national origin, age, disability, and where applicable sex, marital status, familial status, parental status, religion, sexual orientation genetic information, political beliefs, reprisal, or because all or part of an individual’s income is derived from any public assistance program. (Not all prohibited bases apply to all programs.) Persons with disabilities who require alternative means for communication of program information (Braille, large print, audiotape, etc.) should contact USDA’s TARGET Center at (202) 720-2600 (voice and TDD).To file a complaint of discrimination, write USDA, Director, Office of Civil Rights, 1400 Independence Avenue, S.W. Washington, DC 20250-9410 or call (800) 795-3272 (voice) or (202) 720-6382 (TDD). USDA is an equal opportunity provider and employer. Authors Gary L. Miller is a professor, University of North Carolina, Environmental Studies, One University Heights, Asheville, NC 28804-3299.
    [Show full text]
  • Biology, Aquaculture and Medical Use of Seahorse, Hippocampus Spp
    Annual Research & Review in Biology 14(5): 1-12, 2017; Article no.ARRB.34152 ISSN: 2347-565X, NLM ID: 101632869 A Review - Biology, Aquaculture and Medical Use of Seahorse, Hippocampus spp Yuan Yuan Zhang1, Bo-Mi Ryu2 and Zhong-Ji Qian1* 1Key Laboratory of Advanced Processing of Aquatic Products of Guangdong Higher Education Institution, College of Food Science and Technology, Guangdong Ocean University, Zhanjiang 524088, P. R. China. 2School of Pharmacy, University of Queensland, Brisbane, Qld 4072, Australia. Authors’ contributions This work was carried out in collaboration between all authors. Authors YYZ and ZJQ conceived and designed the study. Author YYZ wrote the first draft of the manuscript. Author BMR managed the literature searches. Authors BMR and ZJQ reviewed the first manuscript and wrote the final manuscript. All authors read and approved the final manuscript. Article Information DOI: 10.9734/ARRB/2017/34152 Editor(s): (1) Eugene A. Silow, Institute of Biology, Chair of invertebrate zoology and aquatic ecology, Sukhe-Baator str., 5, Irkutsk, 664003, Russia. (2) George Perry, Dean and Professor of Biology, University of Texas at San Antonio, USA. Reviewers: (1) Weiting Wang, Tianjin Institute of Pharmaceutical Research, China. (2) Jonatas R. de Oliveira, Sao Paulo State University, Brazil. (3) Marina Quartu, University of Cagliari, Italy. Complete Peer review History: http://www.sciencedomain.org/review-history/20049 Received 16th May 2017 Accepted 11th July 2017 Review Article Published 14th July 2017 ABSTRACT Seahorse has been used as medicine in Asian countries such as China, Korea, Japan and Vietnam for thousands of years. However, in western countries, the ecology of seahorse has been a focus of attention of many researchers for years.
    [Show full text]
  • Male Seahorse and Human Pregnancies Remarkably Alike 1 September 2015
    Male seahorse and human pregnancies remarkably alike 1 September 2015 hasn't been known until now is the degree to which male seahorses nourish and protect their embryos in their brood pouch during the 24-day gestation period. Findings co-authored by Dr Camilla Whittington from the University's School of Biological Sciences, published today in Molecular Biology and Evolution, show male seahorses play as much a part in nurturing embryos during pregnancy as female mammals. Previously their role, other than as pouch provider, was largely a mystery. "Surprisingly, seahorse dads do a lot of the same things human mums do," said Dr Whittington. "Seahorse babies get a lot of nutrients via the egg yolk provided by their mothers but the pouch of the fathers has also evolved to meet the complex challenges of providing additional nutrients and immunological protection, and ensuring gas exchange and waste removal. " Dr. Whittington and colleagues found male seahorses are able to deliver nutrients to their developing embryos, particularly energy-rich lipids, and calcium to allow them to build their tiny skeletons. It is likely these nutrients are secreted in the brood pouch and then absorbed by embryos. A newborn Australian pot-bellied seahorse emerges from its fathers pouch. Credit: Rudie Kuiter, Aquatic They also found male seahorses' gene expression Photographics during pregnancy was similar to that of humans. Their research involved taking samples from brood pouches and assessing how gene expression changed during the course of the pregnancy. It is Their pregnancies are carried by the males but, the first RNA sequencing study - monitoring how when it comes to breeding, seahorses have more much genes switch on and off - across the full in common with humans than previously thought, course of pregnancy in any animal.
    [Show full text]
  • Downloaded from Bioscientifica.Com at 10/01/2021 07:31:19PM Via Free Access
    158 5 REPRODUCTIONRESEARCH Melatonin rescues impaired penetration ability of human spermatozoa induced by mitochondrial dysfunction Xue-Ying Zhang1,*, Yi-Meng Xiong1,*, Ya-Jing Tan2, Li Wang2, Rong Li2, Yong Zhang2, Xin-Mei Liu2, Xian-Hua Lin2, Li Jin2, Yu-Ting Hu2, Zhen-Hua Tang2, Zheng-Mu Wu2, Feng-Hua Yin2, Zheng-Quan Wang2, Ye Xiao2, Jian-Zhong Sheng1,3 and He-Feng Huang1,2,4 1The Key Laboratory of Reproductive Genetics (Zhejiang University), Ministry of Education, Hangzhou, Zhejiang, China, 2The International Peace Maternity and Child Health Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai, China, 3Department of Pathology and Pathophysiology, School of Medicine, Zhejiang University, Hangzhou, Zhejiang, China and 4Shanghai Key Laboratory of Embryo Original Diseases, Shanghai, China Correspondence should be addressed to H-F Huang; Email: [email protected] *(X-Y Zhang and Y-M Xiong contributed equally to this work) Abstract Fertilization failure often occurs during in vitro fertilization (IVF) cycles despite apparently normal sperm and oocytes. Accumulating evidence suggests that mitochondria play crucial roles in the regulation of sperm function and male fertility. 3-Nitrophthalic acid (3-NPA) can induce oxidative stress in mitochondria, and melatonin, as an antioxidant, can improve mitochondrial function by reducing mitochondrial oxidative stress. The role of sperm mitochondrial dysfunction in fertilization failure during IVF is unclear. The present study revealed that spermatozoa with low, or poor, fertilization rates had swollen mitochondria, increased mitochondria- derived ROS, and attenuated mitochondrial respiratory capacity. 3-NPA treatment enhanced mitochondrial dysfunction in sperm. Spermatozoa with poor fertilization rates, and spermatozoa treated with 3-NPA, had reduced penetration ability.
    [Show full text]