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Cellular localization and age-dependent changes in mRNA for cyclic adenosine 3',5'-monophosphate-dependent protein kinases in rat testis.

Gonadotropin activation of cyclic adenosine 3',5'-monophosphate (cAMP)-dependent protein kinases plays an important role in the regulation of testicular function. This study was undertaken to establish the expression of various subunits of cAMP-dependent protein kinases in different testicular cell types as well as during sexual maturation. RNA was extracted from cultured Sertoli cells, cultured peritubular cells, germ cells (pachytene spermatocytes, round spermatids), tumor Leydig cells, as well as whole testis from rats of various ages. Messenger RNA levels were studied by Northern analysis using available cDNA probes. The regulatory subunit (R) designated RII51 was found to be predominantly expressed in cAMP-stimulated Sertoli cells and tumor Leydig cells. Much lower levels were found in cultured peritubular cells and germ cells. A 2.9- and 3.2-kb mRNA for the RI subunit were found at about similar levels in all cell types, whereas the smaller 1.7-kb mRNA was expressed in high levels in germ cells. Also, the catalytic subunit (C) of cAMP-dependent protein kinase, designated C alpha, was expressed in all cell types; the highest mRNA levels for this subunit were found in germ cells and in tumor Leydig cells. The 1.7-kb mRNA for androgen-binding protein (ABP) was abundant in cAMP-stimulated Sertoli cells and was not present in other cell types of the testis. Furthermore, the cellular localization of the cAMP-dependent protein kinase subunits was also supported by developmental studies. The mRNA level of the RII51 3.2-kb species was relatively constant until Day 30, after which there was a tendency to decrease. A 1.6-kb message first appeared at greater ages. The mRNA for the smaller 1.7-kb species of RI, as well as the C alpha, showed a significant increase during development, supporting an enrichment of these mRNAs in germ cells. Messenger RNA levels for ABP were not detected in testis from 5- to 10-day-old rats but increased up to Day 30. After this age, mRNA for ABP revealed an age-dependent decrease, which parallels the relative increase of germ cells in the testis. In summary, these results demonstrate a clear pattern of cellular localization of the various mRNA species for subunits of the cAMP-dependent protein kinase in the rat testis.

Age Factors↗

A quantitative study of spermatogenesis in the developing rat testis.

Quantitative (stereological) studies were performed to determine the number of germ cells in the developing rat testis. Sprague-Dawley rats aged 1-70 days were fixed by immersion or perfusion and embedded in Epon Araldite. Blocks of tissue were sectioned at 1.5 microns and stained with toluidine blue dye. Sections were systematically scanned and the areal density of nuclear profiles counted using an unbiased counting frame. Numerical density and absolute number of germ cells in the processed block were then estimated. Corrections for processing shrinkage were determined by comparing the volume of processed and unprocessed samples. The results demonstrate the necessity of determining absolute number rather than volume density (or areal density) in comparing germ cell numbers. In these experiments, spermatogonial numbers stabilized in the range 18.4-23.6 million per testis on Day 30. The number of primary spermatocytes that were first apparent on Day 15 increased rapidly to 54.6 million per testis on Day 30 and then slowly to 73.6 million on Day 70. Round spermatids were first apparent on Day 25 and increased rapidly to 85.7 million per testis on Day 40, then continued to increase to 151.9 million on Day 70. The study provides both methods and baseline data for future experiments involving manipulation of the spermatogenic potential of the testis.

Animals↗

Localization of cellular retinol-binding protein mRNA in rat testis and epididymis and its stage-dependent expression during the cycle of the seminiferous epithelium.

Anatomical localization of cellular retinol-binding protein (CRBP) mRNA was examined in normal rat testis and epididymis and also in retinoid-deficient rat testis. In situ hybridization was performed with 35S-labeled rat CRBP cRNA probes on frozen tissue sections. In normal testis, CRBP mRNA was mainly localized in the Sertoli cells and to some extent in peritubular cells. A distinct cyclic variation of the relative levels of hybridizable CRBP mRNA was observed during the spermatogenic cycle. The peak of CRBP mRNA content was seen in the stages of the cycle that preceded those in which peak CRBP protein content had been observed previously in our laboratory by immunohistochemistry. No appreciable amount of CRBP mRNA was observed in the interstitial space or in the lumen of the tubules. CRBP mRNA displayed the same anatomical localization in the retinoid-deficient testis, but the level of hybridizable CRBP mRNA was substantially reduced. A strong hybridization signal for CRBP mRNA was seen in proximal epididymis and was strikingly localized in the ductular epithelium. CRBP mRNA was not detectable in the distal portion of the epididymis. These studies provide information about the cell-specific expression of CRBP synthesis within the testis and epididymis and about its cyclic variation and regulation.

Animals↗

Expression of E-cadherin in immature rat and mouse testis and in rat Sertoli cell cultures.

Cadherins are Ca(2+)-dependent cell adhesion molecules that play essential roles in organogenesis. Northern blot analysis was used to determine the levels of epithelial (E)-, neural (N)-, and placental (P)-cadherin expression in developing rat testes from 1-, 2-, 3-, and 4-wk-old rats. Highest expression of all three cadherins occurred during the first two postnatal weeks, prior to the establishment of the blood-testis barrier. Transcripts of all three cadherins were also detected in RNA isolated from Sertoli cells cultured from 3-wk-old rat testes. Immunoblot analysis demonstrated levels of E- and P-cadherin protein in the testis and Sertoli cells that corresponded to the levels of their respective RNA transcripts. Immunohistochemical reactivity of E-cadherin in 8-day-old mouse testis was associated with germ cells situated basally in the seminiferous tubules. This report establishes the expression of E-cadherin in the testis and the simultaneous expression of E-, N-, and P-cadherin in both testis and Sertoli cell cultures.

Animals↗

Release and steroidogenic actions of polyunsaturated fatty acids in the goldfish testis.

The aim of the present study was to examine the role of several polyunsaturated fatty acids (PUFA) in the control of steroidogenesis in the goldfish testis. The release of fatty acids from testis tissue in response to the protein kinase C activator phorbol-12-myristate-13-acetate (PMA) and calcium ionophore A23187 was studied. After a 2-h incubation, goldfish testis tissue released detectable amounts of several fatty acids, particularly docosahexaenoic acid (DHA). Treatment with PMA (100 nM) and A23187 (1 microM) increased the release of arachidonic acid (AA) and, to a lesser extent, of eicosapentaenoic acid (EPA). Further experiments showed that AA (100 and 400 microM) and, to a lesser extent, eicosatrienoic acid (ETA; 400 microM)--but not EPA or DHA (both 400 microM)--stimulated testicular testosterone (T) production via an indomethacin (INDO; 40 microM)--sensitive pathway, suggesting that these effects may be mediated through conversion to prostaglandins (PG). E-series PGs formed directly from ETA, AA, or EPA (PGE1, PGE2, or PGE3, respectively) all stimulate T production, with relative potencies of PGE2 > PGE1 > PGE3. The inability to detect ETA release from testis incubates and the limited effect of EPA on steroid production suggest that PGE2 represents the predominant E-series PG formed under physiological conditions in the goldfish testis. The steroidogenic action of AA was blocked by treatment with EPA or DHA, and this effect is due, partly, to inhibition of PGE2 formation from AA.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

Developmental and hormonal regulation of DNA methyltransferase in the rat testis.

Changes in DNA methylation patterns during gametogenesis have been implicated in the regulation of germ cell development and genomic imprinting. Cytosine methylation is catalyzed by the enzyme DNA (cytosine-5)-methyltransferase (DNA MTase). The objective of this study was to determine the presence and study the developmental and hormonal regulation of DNA MTase expression in the rat testis. Northern blots of RNA isolated from 10 different adult rat tissues were used to determine tissue-specific differences in transcript size and abundance of DNA MTase. The developmental regulation of DNA MTase in the rat testis was examined by use of Northern blots of testicular and isolated germ cell RNA from rats ranging in age from 7 to 91 days. For a better understanding of the hormonal regulation of DNA MTase in the rat testis, adult rats were hypophysectomized and 4 wk later (Day 0) received 24-cm testosterone silastic implants; controls were sham hypophysectomized. At Days 0, 3, 7, 14, 28, and 56, one testis from each rat (n = 4/group) was used to prepare total RNA. Examination of DNA MTase mRNA expression in different rat tissues demonstrated the existence of a single 5.2-kb transcript; up to 5-fold tissue-specific variations in the levels of DNA MTase mRNA between the tissue with the highest expression, spleen, and that with the lowest expression, prostate; and significant levels of expression in the testis (three times prostate levels). During testicular development, DNA MTase mRNA levels were highest at 7-21 days of age and decreased by 45% by Day 28; mRNA levels decreased further to reach steady adult levels by Day 42.(ABSTRACT TRUNCATED AT 250 WORDS)

Aging↗

Human fetal testis endoplasmic reticulum glucose-6-phosphatase enzyme protein.

Microsomal glucose-6-phosphatase (EC 3.1.3.9) is an enzyme system traditionally thought to be present only in gluconeogenic tissues. We have used microassay techniques, immunohistochemistry using monospecific antibodies to the liver enzyme, and specific DNA probes and primers to examine whether glucose-6-phosphatase is present in human and rat testis. Microsomal glucose-6-phosphatase activities in human fetal testis (weeks 15-20 of gestation) are approximately 25% of corresponding liver values. Localization is predominantly in Leydig cells, with variable and weak immunoreactivity in developing seminiferous tubules. Kinetic analysis of glucose-6-phosphatase in intact and disrupted microsomes and Southern blot analysis of polymerase chain reaction products indicated that the specific glucose-6-phosphatase enzyme system was also present in rat testis. We have shown for the first time that specific microsomal glucose-6-phosphatase activity, protein, and mRNA are present in testis, and that the predominant site of expression is the Leydig cell in human fetal testis.

Animals↗

Localization of class I and class IV alcohol dehydrogenases in mouse testis and epididymis: potential retinol dehydrogenases for endogenous retinoic acid synthesis.

The vitamin A metabolite retinoic acid plays an essential signaling role in spermatogenesis by acting as a ligand for nuclear retinoic acid receptors. However, little is known about the regulation of retinoic acid synthesis from vitamin A (retinol). Here we have examined mouse testis and epididymis for the presence of endogenous retinoic acid and for the expression of genes encoding class I and class IV alcohol dehydrogenases (ADH), both of which catalyze retinol oxidation, the rate-limiting step in the conversion of retinol to retinoic acid. Using a bioassay we found that mouse testis and epididymis both have significant levels of retinoic acid ranging from 7 to 8 pmol/g, an amount known to be sufficient to optimally activate retinoic acid receptors. In situ hybridization analysis of mouse testis revealed that class I ADH mRNA was localized in Sertoli cells and Leydig cells, while class IV ADH mRNA was confined to late spermatids. In the epididymis, class I ADH mRNA was detected in both principal and basal cells, whereas class IV ADH mRNA was limited to basal cells. Immunohistochemical analyses of testis indicated that class I ADH protein was localized in Sertoli and Leydig cells, whereas class IV ADH protein was observed only in late spermatids. Class I ADH protein was localized in principal and basal cells of the cauda epididymidis but only in basal cells of the caput epididymidis. Class IV ADH protein was limited to basal cells along the entire length of the epididymis. These results support a role for ADHs during spermatogenesis, potentially as retinol dehydrogenases catalyzing local retinoic acid synthesis in the testis and epididymis.

Alcohol Dehydrogenase↗

Characterization of the promoter region of the rat testis-specific histone H1t gene.

Histone H1t is synthesized only in male germ cells during the late pachytene stage of meiosis and is retained in spermatids until the nucleus elongates. Transgenic experiments suggest that spermatocyte-directing sequences lie within 140 base pairs of the cap site. To study the mechanism of this specificity we compared the DNase I footprints made on the immediate promoter regions of H1t and H1d (a typical somatic H1) by testis and liver extracts and observed both common and differentially protected regions. The common footprints of H1t included an Sp1 consensus (GC box 1) and a CCAAT motif. Electrophoretic mobility shift assays (EMSA) identified ubiquitous binding factors for GC box 1 and a binding factor for the CCAAT element that we identified immunologically as H1TF2. H1t-specific footprints occurred over the palindrome CCTAGG and a GC-rich sequence downstream of the TATA box (GC box 2). EMSA analysis of the palindrome identified testis-specific as well as ubiquitous binding factors. UV irradiation of a palindrome-binding reaction generated a cross-linked doublet of about 50 kDa from both testis and liver. Protein factors that bound to the GC box 2 sequence were similar from testis and liver, and GC box 1 and an Sp1 consensus competed for them. In vitro transcription directed by H1t occurred at comparable levels in testis and liver extracts. The importance of both GC box 1 and CCAAT elements was demonstrated by deletion analysis and by oligonucleotide competition. No dependence on the H1t palindrome was observed for in vitro transcription.

Animals↗

Determination of testis temperature rhythms and effects of constant light on testicular function in the domestic fowl (Gallus domesticus).

There is a wide range of opinions regarding the operating temperature of the testis in the domestic fowl. We used physiological monitoring techniques to investigate testis and body temperature over daily periods and under various light regimes to elucidate body temperature gradients in the fowl. We confirm that the operating temperature of the adult fowl's testes is equivalent to core body temperature (40-41 degrees C). Long-term continuous temperature monitoring showed that there was no difference between the temperature of the testis, liver, and peritoneum during a 24-h period either in a normal light:dark cycle or under constant light conditions. However, there was a slight decrease in all temperatures at subjective night in each case, a decrease that does not appear to be sufficient to influence spermatogenesis. Birds maintained under constant light throughout two cycles of the seminiferous epithelium (28 days) still exhibited normal testis function and structure, even when "nightly" testis temperature decrease was the lowest. Thus, by undergoing spermatogenesis at an elevated temperature, the domestic fowl system is unique among the homeothermic animal systems studied to date.

Animals↗

Characterization of lymphocytes in the adult rat testis by flow cytometry: effects of activin and transforming growth factor beta on lymphocyte subsets in vitro.

The rat testis is considered to be an immunologically privileged site because of its reduced capacity to support antigen-specific immune responses. To understand this phenomenon, it is essential to characterize both the lymphocyte subpopulations normally present in the testis and their regulation by testicular cytokines. Peripheral blood was obtained from adult male Dark Agouti or Sprague-Dawley rats, and testicular interstitial tissue was collected after perfusion of the testes to remove blood. Blood and testis lymphocytes were isolated using discontinuous Percoll density gradients, and the testicular lymphocytes were further purified by selective adherence to remove mononuclear phagocytes. The isolated lymphocytes were analyzed by flow cytometry using specific monoclonal antibodies and fluorescein labeling and were enumerated as total T cells, CD4+ T cells, CD8+ T cells, B cells, and natural killer (NK) cells. In contrast to peripheral blood, in which the CD4+ T-cell subset was the major lymphocyte subset, rat testis T cells were predominantly of the CD8+ subset, and a large population of NK cells also were present. Subsequently, peripheral blood lymphocytes were stimulated with the polyclonal T-cell activator, phytohemagglutinin, and cultured in the presence of activin, inhibin, or transforming growth factor beta (TGFbeta) prior to flow cytometric analysis. Activin and TGFbeta suppressed T-cell proliferation without any selective effect on either T-cell subset, and inhibin had no effect. The predominance of CD8+ T cells and NK cells, and the relatively minor proportion of CD4+ T cells, are consistent with both increased cellular immune surveillance and a reduced capacity for initiating antigen-specific immune responses in the adult rat testis.

Activins↗

Differentiation of adult Leydig cells in the neonatal rat testis is arrested by hypothyroidism.

The effects of propyl thiouracil (PTU)-induced hypothyroidism on testicular interstitial cells and androgen secretion in vitro in the neonatal rat were investigated using Sprague Dawley rats of 1, 7, 14, and 21 days. The results revealed that the fetal Leydig cell (FLC) number per testis was unchanged between and within treatment groups at all ages tested. FLC size was 50% smaller in 21-day controls than in all other groups. Adult Leydig cells (ALCs) were present at Days 14 and 21 in controls but were absent in PTU rats. ALCs approximated FLCs of 21-day controls in size. ALC number per testis showed a sharp increase at Day 21. 11ss-HSD1-positive cells were absent in 21-day PTU testes, but a few were present in 21-day control testes. Testosterone secretion per testis was unchanged in 1- to 21-day controls and 7- to 21-day PTU rats. However, at Day 21, a significantly lower value was seen in controls compared to PTU rats. Testicular androstenedione secretion was not significantly different between control and PTU rats up to 14 days, but a sharp rise was observed in controls at Day 21. At this age, androstenedione levels in PTU rats were similar to those at younger ages. In summary, histological studies showed that hypothyroidism prevented the hypotrophy of FLC and the emergence of ALC in the neonatal rat testis, and agreed favorably with results concerning testicular androgen secretion in vitro. These findings suggest that thyroid hormones have a regulatory role in precursor cell differentiation into Leydig cells in the neonatal rat testis to establish the ALC population.

11-beta-Hydroxysteroid Dehydrogenases↗

Cloning and expression analysis of testis-specific cyclic 3', 5'-adenosine monophosphate-responsive element modulator activators in the nonhuman primate (Macaca fascicularis): comparison with other primate and rodent species.

The cAMP-responsive element modulator (CREM) gene encodes a transcription factor that is essential for spermatogenesis. In mouse testis, several CREM repressors and activators have been identified. In contrast to the situation for the mouse, however, little is known about CREM isoforms in the primate testis. We analyzed CREM isoforms and mRNA expression in a clinically relevant primate model, the cynomolgus monkey (Macaca fascicularis). A cDNA library was generated from monkey testis; and two activator isoforms (tau2 with and without exon gamma) were identified, which displayed high sequence identity to mouse and human isoforms. The insertion of exon gamma was observed for the first time in the primate testis. CREM activator expression was confined to the testis, where it was seen in late pachytene spermatocytes and round spermatids in specific spermatogenic stages, as revealed by in situ hybridization. Comparison of the mRNA and the recently described protein expression indicated a lack of translational delay of CREM expression. Comparative analysis of testicular CREM expression by reverse transcription-polymerase chain reaction yielded several transcripts in the rat, mouse, hamster, and marmoset; two transcripts in cynomolgus and rhesus monkeys; and one transcript in men. These findings suggest an evolutionary trend from multiple activator isoforms to a single activator transcript in men.

Amino Acid Sequence↗

Testis transplantation in male rainbow trout (Oncorhynchus mykiss).

The objective of the present study was to establish a procedure for the transplantation of an intact testis from one male rainbow trout (Oncorhynchus mykiss) to another individual and evaluate the reproductive function of the transplanted testis at sexual maturity. Isogenic (cloned) male rainbow trout were produced by crossing a completely homozygous male (YY) with a homozygous female (XX) to eliminate any problem of tissue rejection. Transplantation was performed on four pairs of sexually immature animals (n = 8); each served both as a donor and recipient. The left testis was removed by making a ventral midline incision to expose the body cavity and gonads. The left testis was disconnected at the anterior and posterior points of attachment and transferred to the recipient fish where it was placed in position adjacent to the pyloric cecae. The right testis was left intact. After 4 wk, the fish were injected (i.p.) twice weekly for 8 or 9 wk with salmon pituitary extract (1.5 mg/kg) to induce precocious sexual maturation. A similar number of untreated fish were maintained as controls. Following this treatment, all the fish were killed, and the right (intact) and left (transplanted) testes were removed, weighed, and sampled for sperm. Although the mean weights of the left, transplanted testes were significantly (P: < 0.05) smaller than the intact testes (transplants = 1.2 g; intact = 3.9 g), transplanted testes were present in all animals, had increased in mass, and were sexually mature containing sperm. The mean fertility, as measured by the proportion of eggs completing first cleavage, of sperm derived from transplanted testes (92%) was no different from the sperm obtained from intact testes (84%). Similarly, there was no difference in the number of embryos attaining the eyed stage of development, after 18 days of incubation, that were derived from transplanted (84%) or intact testes (85%).

Animals↗

Functional analysis of stem cells in the adult rat testis.

Adult stem cells maintain several self-renewing systems and processes in the body, including the epidermis, hematopoiesis, intestinal epithelium, and spermatogenesis. However, studies on adult stem cells are hampered by their low numbers, lack of information about morphologic or biochemical characteristics, and absence of functional assays, except for hematopoietic and spermatogonial stem cells. We took advantage of the recently developed spermatogonial transplantation technique to analyze germ line stem cells of the rat testis. The results indicate that the stem cell concentration in rat testes is 9.5-fold higher than that in mouse testes, and spermatogenic colonies derived from rat donor testis cells are 2.75 times larger than mouse-derived colonies by 3 mo after transplantation. Therefore, the extent of spermatogenesis from rat stem cells was 26-fold greater than that from mouse stem cells at the time of recipient testis analysis. Attempts to enrich spermatogonial stem cells in rat testis populations using the experimental cryptorchid procedure were not successful, but selection by attachment to laminin-coated plates resulted in 8.5-fold enrichment. Spermatogonial stem cells are unique among adult stem cells because they pass genetic information to the next generation. The high concentration of stem cells in the rat testis and the rapid expansion of spermatogenesis after transplantation will facilitate studies on stem cell biology and the introduction of genetic modifications into the male germ line. The functional differences between spermatogonial stem cells of rat vs. mouse origin after transplantation suggest that the potential of these cells may vary greatly among species.

Animals↗

Expression of tumor necrosis factor-alpha-related apoptosis-inducing ligand and its receptors in rat testis during development.

Tumor necrosis factor-alpha-related apoptosis-inducing ligand (TRAIL) is a member of the tumor necrosis factor-alpha family of cytokines that is known to induce apoptosis upon binding to its death domain-containing receptors, DR4/TRAIL-R1 and DR5/TRAIL-R2. Two additional TRAIL receptors, DcR1/TRAIL-R3 and DcR2/TRAIL-R4, lack functional death domains and act as decoy receptors for TRAIL. In this study, the presence of TRAIL and its receptors was investigated in the rat testis during development. TRAIL and its receptors were immunolocalized to the different testicular cell types. TRAIL and its receptors were also identified in the rat testis in terms of protein and mRNA. Our immunohistochemical studies indicate that TRAIL, DR5/TRAIL-R2, and DcR2-TRAIL-R4 are detected in Leydig cells, whereas ligand and all receptors are localized in germ cells. TRAIL was permanently immunodetected in germ cells from the fetal stage to adulthood, whereas its receptors were immunolocalized exclusively in postmeiotic germ cells. The expression of TRAIL and receptor mRNAs was consistent with the immunodetection of TRAIL and receptor proteins. Indeed, TRAIL ligand mRNA was also identified in the rat testis from the fetal stage to adulthood. The mRNAs of the death receptors, DR4/TRAIL-R1 and DR5/TRAIL-R2, were weakly detected during the perinatal period and increased from the pubertal stage to adulthood. The mRNAs of the decoy receptors, DcR1 and DcR2, were present in the rat testis at all ages studied, but the DcR2/TRAIL-R4 mRNa level was higher from the pubertal period to adulthood. Together, the present findings demonstrate that 1) TRAIL and its receptors are expressed in the testis during normal development, and 2) TRAIL protein is present in the different germ cell types, whereas its receptors were predominantly detected in the postmeiotic germ cells.

Aging↗

Microlithiasis of the epididymis and the rete testis.

Testicular microlithiasis is a well-defined clinical and pathologic entity easily diagnosed through testicular echography; however, its association with cancer and infertility is now under debate. Many efforts have been done in recent years to clarify the spectrum of lesions observed in testicular microlithiasis, but no published data as to the existence of a possible microlithiasis of the epididymis and the rete testis have been found. We have observed microlithiasis of the epididymis and the rete testis in surgical (8 epididymis and 6 testis) and autopsy specimens (12 cases). In decreased order of frequency, microliths of the proximal spermatic way were seen in rete testis, epididymal duct, and efferent ducts. Intraluminal, subepithelial, and interstitial microliths were localized along these segments of the spermatic way. Subepithelial microliths were the most frequently found. A granulomatous reaction around the interstitial epididymal microliths, mimicking malacoplakia, was observed in 1 case. The differential diagnosis of microliths includes corpora amilacea, Michaelis-Gutmann bodies, calcium deposits, hyaline globules, and parasites, like the giant kidney worm Dioctophyme renale. In infants and young adults, microlithiasis of the epididymis and the rete testis is frequently associated with alterations in the development of the proximal spermatic way. In elderly adults, it is related to ischemia and obstruction of the spermatic way.

Adolescent↗

Novel noncoding RNA from human Y distal heterochromatic block (Yq12) generates testis-specific chimeric CDC2L2.

The human Y chromosome, because it is enriched in repetitive DNA, has been very intractable to genetic and molecular analyses. There is no previous evidence for developmental stage- and testis-specific transcription from the male-specific region of the Y (MSY). Here, we present evidence for the first time for a developmental stage- and testis-specific transcription from MSY distal heterochromatic block. We isolated two novel RNAs, which localize to Yq12 in multiple copies, show testis-specific expression, and lack active X-homologs. Experimental evidence shows that one of the above Yq12 noncoding RNAs (ncRNAs) trans-splices with CDC2L2 mRNA from chromosome 1p36.3 locus to generate a testis-specific chimeric beta sv13 isoform. This 67-nt 5'UTR provided by the Yq12 transcript contains within it a Y box protein-binding CCAAT motif, indicating translational regulation of the beta sv13 isoform in testis. This is also the first report of trans-splicing between a Y chromosomal and an autosomal transcript.

Adult↗