2P1, a novel male mouse cDNA specifically expressed during meiosis

We screened a mouse germinal cell expression library with a probe derived from Sob1, a human testis-specific cDNA, and identified 2P1, a new mouse cDNA. A database search revealed that 2P1 was 91% identical to ORF1 of E3-3, a rat gene probably involved in the regulation of alternative splicing. Sequencing showed that 2P1 has a destabilization motif in its 3'-untranslated region. Northern blotting showed strong gene expression in the testis and weak expression in the epididymis, with no signal detected in other tissues. RT-PCR analysis confirmed testis and epididymis expression. In situ hybridization revealed that 2P1 mRNA was absent in spermatogonia but expressed in spermatocytes. This last result was confirmed by RT-PCR of FACS isolated primary spermatocytes (pachytene stage). Using RT-PCR, purified spermatids were also shown to express 2P1.     

Ultrastructural evidence for Sertoli-like cells in the testis of the asteroid,Luidia clathrata (Say) (Echinodermata: Platyasterida)

Non-germinal cells arise adjacent to the basal lamina and extend between the numerous germinal celli. Nuclei of these non-germinal cells may be positioned near the basal lamina or more peripherally between the spermatocytes. Thin cytoplasmic processes extend between the spermatocytes to the spermatids. These cytoplasmic processes vary in electron density from the cytoplasm of the germinal cells. These non-germinal cells closely resemble the vertebrate Sertoli cell.     

The Fine Structure of the Testis of a Lancelet (=Amphioxus), Branchiostoma floridae (Phylum Chordata: Subphylum Cephalochordata= Acrania)

The germinal and non-germinal cells of the ripe lancelet testis are described by transmission electron microscopy. The visceral peritoneum of the testis is composed of myoepithelial cells, and the haemal layer consists of regions of narrow sinuses and conspicuously thicker blood vessels filled with blood plasma and bounded by basal laminae. Within the germinal epithelium and the testicular lumen, the non-germinal cells, which are not abundant, contain conspicuous lysosomes and mitochondria with tubular cristae, indicating that they may be involved in steroid synthesis. In the ripe testis, the non-germinal cells do not appear to be organized into a blood-testis barrier. Ail types of spermatogenic cells may be flagellated and are joined in small groups by intercellular bridges. During differentiation of the spermatids, the Golgi complex is associated with formation of the acrosomal vesicle near the posterior pole of the cell. A remarkable feature is the dual origin of the subacrosomal material: one component originates at the posterior end of the spermatid, and the other at the anterior end. Subsequently, the two components merge into one after the acrosomal vesicle has migrated to its definitive anterior position in the mature spermatozoon.     

Molecular cloning and differential expression of somatic and testis-specific H2B histone genes during rat spermatogenesis

We have cloned cDNA of a testis-specific histone, TH2B (a variant of H2B), and rat somatic H2B gene to investigate regulation of testis-specific histone genes during rat spermatogenesis. The amino acid sequences deduced from DNA sequences show extensive sequence divergence in the N-terminal third of the two histones. The rest is highly conserved. One cysteine residue was found in TH2B. No cysteine is present in somatic histones except in H3 histone. We investigated the expression of TH2B and H2B genes using the regions of sequence divergence as hybridization probes. The TH2B gene is expressed only in the testis, and the expression of this gene is detected 14 days after birth, reaching a maximum at Day 20. The level of H2B mRNA shows a reciprocal pattern. This contrasting pattern can be explained by the gradually changing proportion of spermatogonia and spermatocytes with testicular maturation. In situ cytohybridization studies show that H2B gene is expressed primarily in proliferating spermatogonia and preleptotene spermatocytes, whereas TH2B gene is expressed exclusively in pachytene spermatocytes which first appear in testis about 14 days after birth. H2B and TH2B genes appear to be ideal markers for the study of proliferation and differentiation events in spermatogenesis and their regulatory mechanisms.