|
| |
| | Sex determination in Hymenoptera |
 | | Regardless of such homologies, it seems clear that the sex determination systems of the Hymenoptera reflect in many ways the peculiar life histories and conditions of individual species. | | | This information, which locates loci near the sex determining locus, sheds little light on sex determination, but may be useful for future studies. | | | While in recent years evidence has mounted that a great number of biological pathways are conserved across the animal kingdom, one developmental process which for the most part has evaded this grand display of commonality is that of sex determination, which in contrast seems to have evolved rather rapidly (Marín and Baker, 1998). |
|
http://www.sccs.swarthmore.edu/users/99/mahowald/hymenoptera.html
(4726 words)
|
|
| |
| | Sex Determination |
| | It seems likely that the sex determination pathway will be related to that of Drosophila melanogaster subsequent to the action of the sexlethal gene, which does not appear to be involved in sex determination in other groups of Diptera (Martin & Lee 1999). | | | Martin, J. Interrelation of inversion systems in the midge Chironomus intertinctus (Diptera: Nematocera) I. A sex-linked inversion. | | | A similar MD system probably also occurs in other Nematocera, such as mosquitoes and blackflies, and may even extend to some of the higher Diptera. |
|
http://www.genetics.unimelb.edu.au/Martin2/sexdt.html
(690 words)
|
|
| |
| | Ch21.doc |
| | In addition to the primary sex organs that produce and carry gametes, many vertebrates develop secondary sex characteristics that are important in sex recognition, as signals of sexual maturity and receptivity, in courtship behavior, and sometimes in combat among males for access to females (Fig. | | | The environmental condition in which the eggs develop is an important determinant of sex in many other vertebrates. | | | The male sex hormones are cortical androgen, produced by the adrenal cortex, and testosterone, produced by the interstitial cells of the testis; the female hormones are estrogen and progesterone, secreted by the ovarian follicles and corpora lutea. |
|
http://www.bio.umass.edu/biology/bemis/FAOV4/Ch21.doc
(7245 words)
|
|
| |
| | Sex determination of Cannabis - Genetic, environmental, or both? - Marijuana Growing |
| | All sex-determination systems are enzyme/hormone/chemically controlled, but the triggering mechanisms for the determination systems vary from purely chromosome-controlled to purely environmental. | | | The genetic-afficionado's approach is that it is determined at pollination, and they base their arguements on the human and mammal XX/XY chromosome-determination system. | | | Some species have their sex determined by bacterial infections, and others again practice sex-changes, where they start out as one gender and changes sex during their lifetime. |
|
http://www.overgrow.com/edge/showthread/t-466228.html
(7245 words)
|
|
| |
| | 1001.txt |
| | The hermaphrodite condition appears to result from the modification of a basic male/female sex-determination system, which permits both spermatogenesis and oogenesis to occur within a female soma. | | | The relative expression of these five genes was determined by measuring the efficiencies of suppressers against amber mutations in genes affecting the nervous system, hypodermis, muscle, and sex determination. | | | Both somatic and germline aspects of sex determination are affected. |
|
http://biosci.umn.edu/CGC/Bibliography/1001.txt
(8999 words)
|
|
| |
| | SWA3Sex.doc |
| | Many other organisms have environmental sex determination (ESD). | | | Some species of fish, for example, are sequential hermaphrodites that change their sex one or more times over the course of their lifetime. | | | Sex in these species is determined by fertilization: fertilized eggs develop into diploid females, and unfertilized eggs develop into haploid males. |
|
http://webpub.alleg.edu/dept/bio/bio340/SWA/SWA3Sex.doc
(519 words)
|
|
| |
| | Sex-determination system - Hutchinson encyclopedia article about Sex-determination system |
| | Most fish have a very flexible system of sex determination, which can be affected by external factors. | | | For example, in wrasse all individuals develop into females, but the largest individual in each area or school changes sex to become the local breeding male. | | | Process by which the sex of an organism is determined. |
|
http://encyclopedia.farlex.com/Sex-determination+system
(277 words)
|
|
| |
| | MCDB 2150 -- Lecture 11 |
| | XY males are hemizygous: One of the features of an X/Y sex chromosome system is that females have two copies of the X chromosome, one of which is inherited from each parent, whereas males have only one, inherited from the mother, and paired with a Y chromosome inherited from the father. | | | Patterns of inheritance: In this lecture, we will focus primarily on patterns of inheritance in the XX/XY system in mammals, including humans, and in Drosophila, with some brief references to other systems. | | | However, individuals of both sexes normally express low levels of the hormones associated primarily with the other sex, and cases can be found within the usually accepted range of normalcy where there is some degree of expression of facial hair in women or breast enlargement in men. |
|
http://www.colorado.edu/MCDB/MCDB2150Fall/notes/L11.html
(277 words)
|
|
| |
| | Encyclopedia: X |
| | Semiotics - also known as semiology - is the study of signs, both individually and grouped in sign systems, and includes the study of how meaning is transmitted and understood. | | | The system of Roman numerals is a numeral system originating in ancient Rome, and was adapted from Etruscan numerals. | | | The MPAA film rating system is a system used in the United States and instituted by the Motion Picture Association of America to rate a movie based on its content. |
|
http://www.nationmaster.com/encyclopedia/X
(6962 words)
|
|
| |
| | EVOLUTIONARY BIOLOGY: ON CHROMOSOMES AND SEX DETERMINATION |
| | There is an even wider range of sexual systems in teleost fishes, with examples of self-fertilizing hermaphrodites [2], sequential hermaphrodites [3], and environmental sex determination [1]. | | | Even within tetrapod vertebrates, however, there is a wide diversity of sex determination mechanisms, with many examples of species with genetic sex determination but microscopically similar X and Y chromosomes, and numerous cases of environmental sex determination [1]. | | | But how does sex achieve this effect, and under what circumstances is it worthwhile? |
|
http://scienceweek.com/2004/sc041112-3.htm
(1024 words)
|
|
| |
| | Talk:Sex-determination system - Wikipedia, the free encyclopedia |
| | From the definition, one could conclude that a sex-determination system is a method that, when applied to a certain individual, tells you whether that individual is a male or a female. | | | In that sense, a sex-determination system for dogs would be "look if you can find testicles". | | | I have read information to the effect that the WW:WZ system for birds AND snakes, (i'm not sure about insects) is a reverse xy system in that as the articles says two of the same chromosomes are needed for male determination, instead of the XX style in human. |
|
http://www.wikipedia.org/wiki/Talk:Sex-determination_system
(312 words)
|
|
| |
| | (WO 01/52726) CLASSIFICATION SYSTEM FOR SEX DETERMINATION AND TISSUE CHARACTERIZATION |
| | The method of sex determination provides additional information about primary sources of systematic tissue variability, namely, the thickness of the dermis and the subcutaneous fat. | | | (57) Instrumentation and procedures for noninvasively determining the sex of human and animal subjects in vivo have been developed based on the irradiation of skin tissue with near infrared light. | | | Categorization of subjects on the basis of the determination is therefore suitable for further spectral analysis and the measurement of biological and chemical compounds, such as blood analytes. |
|
http://www.wipo.int/ipdl/IPDL-CIMAGES/view/pct/getbykey5?KEY=01/52726.010726
(195 words)
|
|
| |
| | Infectious Sex |
| | One of the most interesting environmental changes in sex determination involves sex changes attendent upon infection with a microorganism. | | | However, in several wild populations, this system is overridden by cytoplasmic sex factors produced by endocytic bacteria. | | | In the woodlouse Armadillium vugare (a terrestrial isopod), sex determination in some populations is determined by a symbiotic bacterium. |
|
http://zygote.swarthmore.edu/sex9.html
(198 words)
|
|
| |
| | Rapid Deadenylation and Poly(A)-Dependent Translational Repression Mediated by the Caenorhabditis elegans tra-2 3' Untranslated Region in Xenopus Embryos -- Thompson et al. 20 (6): 2129 -- Molecular and Cellular Biology |
| | tra-2 encodes a membrane protein and may mediate cell communication in the Caenorhabditis elegans sex determination pathway. | | | Puoti, A., Pugnale, P., Belfiore, M., Schlappi, A.-C., Saudan, Z. RNA and sex determination in Caenorhabditis elegans: Post-transcriptional regulation of the sex-determining tra-2 and fem-3 mRNAs in the Caenorhabditis elegans hermaphrodite. | | | In several systems, regulated changes in poly(A) length are correlated with changes in translational activity. |
|
http://mcb.asm.org/cgi/content/full/20/6/2129
(6467 words)
|
|
| |
| | X-chromosome: Definition and Much More From Answers.com |
| | Chromosomal conditions involving the sex chromosomes often affect sex determination (whether a person has the sexual characteristics of a male or a female), sexual development, and the ability to have children (fertility). | | | The sex chromosome associated with female characteristics, occurring paired in the female and singly in the male sex-chromosome pair. | | | The sex chromosome associated with female characteristics in mammals, occurring paired in the female and single in the male. |
|
http://www.answers.com/topic/xy-sex-determination-system
(1212 words)
|
|
| |
| | Sex Determination |
| | Refined Techniques of FEMcide: foetal sex-determination and sex pre selection/te... | | | The Role of Estrogen in Turtle Sex Determination and the Effect of PCBs... | | | Sex determination and sex linkage in water frogs... |
|
http://www.scienceoxygen.com/biology/360.html
(304 words)
|
|
| |
| | Minna Heikkilä. Development of the adreno-genital system. ISBN 951-42-6844-X |
| | After sex determination Wnt-4 was downregulated in the testis, but the expression persisted until birth in the ovary. | | | Although the genetic sex of an embryo is determined at conception by the presence or absence of the Y chromosome, both females and males have bipotential, undifferentiated gonads early in their development. | | | Wnt-4-deficient female mice demonstrated a partial female-to-male sex reversal and a reduction in the number of oocytes, while the Müllerian duct was absent from both sexes. |
|
http://herkules.oulu.fi/isbn951426844X
(289 words)
|
|
| |
| | Human Anatomy Chapter 27 -- Evolution Atlas |
| | The second function is responsible for the evolution of sex and gender. | | | Sexual individuals that reproduce in a way that produces diverse offspring is much more likely to be genetically represented in future generations than asexual individuals that reproduce genetically identical offspring by mitosis. | | | The main functions of the reproductive system are to 1) reproduce, and 2) produce genetically diverse offspring. |
|
http://cwx.prenhall.com/bookbind/pubbooks/martini10/chapter27/custom2/deluxe-content.html
(289 words)
|
|
| |
| | VE Glossary |
| | Part of nervous system, which regresses from tip of spinal column up until third lumbar vertebrae at time of birth | | | Ectodermal thickening in amniotic sac floor; Forerunner of nervous system (spinal cord and brain) | | | Embryonic tissue layer that develops into muscles, bones and circulatory system |
|
http://www.visembryo.com/baby/gloss.html
(4499 words)
|
|
| |
| | Eulimnadia |
| | Step 4: Derive equations describing the biological system | | | Parameter: "An arbitrary constant whose value describes a characteristic of a system" | | | A number of evolutionary questions arise in this system: |
|
http://www.zoology.ubc.ca/~otto/Talks/Shrimp/Talk.html
(614 words)
|
|
| |
| | Wolbachia in Humans? |
| | infection, hence, when they reproduce, no Wolbachia are reproduced.) Pill bugs have a WZ sex-determination system, in contrast to the more common XY system found in humans. | | | a Darwinian perspective, it makes sense for Wobachia to favor the sex that can support the | | | plants as corn and rye that the mitochondrion is responsible for skewing the sex ratio in |
|
http://www.ejnerfulsang.com/Wolbachia.html
(614 words)
|
|
|
