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After meiosis each spermatid get either the X chromosome or the Y chromosome. I know that the 4 spermatids formed from 1 spermatogonia are connected by cytoplasm and so the proteins made by X or Y chromosome can be shared by all the 4 cells.

I want to know what proteins made by X or Y chromosome are exclusive to the X or Y chromosome and are needed to convert spermatids to sperms.

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Are you asking what proteins are exclusive to X and Y from all other chromosomes or are you asking which proteins are on the X but not the Y (and vice versa)? These are two very different questions. –  Armatus Sep 30 '13 at 19:02
    
@Armatus I am asking for genes present exclusively on X or exclusively on Y which are needed to convert spermatids to sperms. –  biogirl Sep 30 '13 at 19:05
    
@Armatus In simpler words the gene should be present strictly on either X or Y not on both. It should also not be present on autosomes. –  biogirl Sep 30 '13 at 19:07
    
I can't think of a particular reason why there would be a need for genes involved in spermatogenesis to be located on the X or Y, all genes involved could simply be on autosomes. I don't know whether any are though (or aren't). –  Armatus Oct 1 '13 at 0:26
    
@Armatus It is actually written in tortora and derrickson that the cells are joined by their cytoplasm because of some genes are exclusive to X or Y but I can't find any proteins meeting this criteria. Even I don't know why they couldn't simply be on any autosome. –  biogirl Oct 1 '13 at 17:26

1 Answer 1

X chromosome has many important genes required for general housekeeping. So we need not really talk about X-chromosome genes. Here is a list of genes present on the X-chromosome.

@Armatus, if all those genes were on autosomes then presence of Y wont be mandatory for male development. There are autosomal genes that are involved in sexual development for e.g. Anti-Mullerian Hormone gene is present on chromosome 19. However, there is must be a master regulator that is male specific and since sex determination is chromosomal in mammals, the Y-chromosome must encode that master regulator.

Sry, encoded in Y-chromosome, is one such protein that is absolutely essential for male sexual development. Having said that, it could be very well possible that the basic genes required in the process of spermatogenesis are autosomally encoded. In fact it is so. I just took the list of genes that were associated with sepermatogenesis in KEGG and checked their chromosomal locations. They are all autosomal.

Gene --- position
SPATA1  ---  1p22.3
SPATA25  ---  20q13.12
SPATA32  ---  17q21.31
SPATA9  ---  5q15
SPATA19  ---  11q25
SOHLH1  ---  9q34.3
SPATC1L  ---  21q22.3
SPATA18  ---  4q12
SPATA2  ---  20q13.13
SPATA21  ---  1p36.13
SPATA2L  ---  16q24.3
GMCL1  ---  2p13.3
SPATA7  ---  14q31.3
SPATA5  ---  4q28.1
SPATA6L  ---  9p24.2
SPATA4  ---  4q34.2
SPATA24  ---  5q31.2
SPATS2L  ---  2q33.1
SPATA16  ---  3q26.31
SPATA6  ---  1p33
SPATA12  ---  3p14.3
SPATS1  ---  6p21.1
SPATC1  ---  8q24.3
SPATA22  ---  17p13.3
SOHLH2  ---  13q13.3
SPATA13  ---  13q12.12
SPATS2  ---  12q13.12
SPATA20  ---  17q21.33
ASUN  ---  12p11.23
SPATA8  ---  15q26.2
SPATA17  ---  1q41
SPATA3  ---  2q37.1
SPATA5L1  ---  15q21.1
GMCL1P1  ---  5q35.3
SPATA41  ---  15q26.3
SPATA42  ---  1p13.3
SPATA33  ---  16q24.3
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If the genes involved in spermatogenesis are all autosomal, then what is the point of having a connected cytoplasm ? Is it because of X chromosome's proteins which are involved in spermatogenesis ? How can I search for those proteins ? –  biogirl Oct 5 '13 at 18:17
    
i dont understand what you are trying to ask here : "then what is the point of having a connected cytoplasm" ? How to find X chromosomal proteins: find all the genes involved in spermatogenesis and find their locations. So the list that i posted is what i obtained in KEGG when i searched for spermatogenesis; no gene from this list is on the X chromosome. But this this may not be exhaustive. –  WYSIWYG Oct 6 '13 at 9:05
    
I will quote a paragraph from Bruce Alberts : " Unlike oocytes sperm undergo most of their differentiation after nuclei have completed meiosis to become haploid.The presence of cytoplasmic bridges between them means that each haploid sperm shares a common cytoplasm with its neighbor.In this way,it can be supplied with all the proteins of a complete diploid genome. Developing chromosome that carry Y chromosome ,for example, can be supplied with essential proteins encoded by genes on the X chromososme.Thus, the diploid genome directs sperm differentiation just as it directs the eggs's." –  biogirl Oct 6 '13 at 18:31
    
This is given on pg 1149 chp 20 fourth edition. –  biogirl Oct 6 '13 at 18:32
    
you are confusing different things here... the products of the diploid genome is used to nourish the sperms.. Some X-chromosomal genes are involved in basic housekeeping functions and their products are involved in this nourishment process... This doesn't mean that X-chromosome genes are involved in spermatogenesis.. Analogous situation: Neurons require glucose to thrive. That doesn't mean that hexokinase is involved in neurogenesis. –  WYSIWYG Oct 7 '13 at 4:02

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