Animal Reproduction Science 64 2000 65–75
Detection of growth factors in the testis of roe deer Capreolus capreolus
Asja Wagener, Steffen Blottner, Frank Göritz, Jörns Fickel
∗
Institute for Zoo Biology and Wildlife Research, Alfred-Kowalke-Straße 17, D-10315 Berlin, Germany Received 15 November 1999; received in revised form 20 June 2000; accepted 18 July 2000
Abstract
Roe deer is a seasonal breeder characterised by a short rutting season in summer. Mature males show synchronised cycles of testicular involution and recrudescence. Therefore, this species is a
valuable model to study seasonal regulation of spermatogenesis in ruminants. It is hypothesised that a time-dependent production of testicular growth factors is required to regulate seasonal changes
in testis growth and spermatogenesis. To identify potential candidates, total RNA from roe deer testis tissue was extracted at three different seasonal periods April, August, December, and us-
ing RT-PCR the presence of several growth factors aFGF, bFGF, IGF-I, IGF-II, TGF-
a, TGF-b
1
, TGF-
b
3
and two isoforms of VEGF was detected. Sequencing of the growth factor PCR fragments revealed a high sequence homology between cattle and roe deer. To further explore the expression
patterns of the identified growth factors in roe deer their expression levels were standardised using glyceraldehyde-3-phosphate dehydrogenase GAPDH gene expression. The study demonstrates
the expression of several growth factors in roe deer testis and supports the assumption of their sea- sonally diverse regulation. These results provide the basis to investigate the role of growth factors in
the regulation of circannual changes of testicular activity. © 2000 Elsevier Science B.V. All rights reserved.
Keywords: Growth factors; Gene expression; Testis; Seasonal dynamics; Roe deer
1. Introduction
The reproductive success of male animals requires the production of competent sperm cells. This process includes the proliferation and differentiation of spermatogenic cells in
testis tissue as well as programmed cell death apoptosis. Animal species with a seasonal reproductive activity such as roe deer, undergo cyclic changes of testicular involution and
∗
Corresponding author. Tel.: +49-30-5168726; fax: +49-30-5126104. E-mail address: fickelizw-berlin.de J. Fickel.
0378-432000 – see front matter © 2000 Elsevier Science B.V. All rights reserved. PII: S 0 3 7 8 - 4 3 2 0 0 0 0 0 1 9 1 - 3
66 A. Wagener et al. Animal Reproduction Science 64 2000 65–75
recrudescence during the transitions between breeding and non-breeding periods. There- fore, they require mechanisms for the stimulation of cell proliferation and spermatogenesis
during testis growth, and also for cell apoptosis during testis involution. These mechanisms require participation of hormones such as testosterone. The production of testosterone by
Leydig cells seems to ensure the survival of germ cells Tapanainen et al., 1993; Thompson, 1994. The hormonal regulation of the changes in testis growth is mediated by paracrine and
autocrine effects of different growth factors. Growth factors are key regulator molecules which affect cell proliferation, meiosis and differentiation. Several growth factors such as
FGFs, IGFs, TGFs have been isolated from testis tissue and evidence suggests that these factors play a role in the control of spermatogenesis for review: Lamb, 1993; Spiteri-Grech
and Nieschlag, 1993; Kierszenbaum, 1994; Smith and Conti, 1996. These investigations were mostly carried out with non-seasonal laboratory animals or in vitro studies. How-
ever, very little is known about the regulation of spermatogenesis in seasonally breeding ruminants. In deer species, so far only involvement of endocrine IGF-I in seasonal growth
processes has been shown; for example in red deer by a correlation of the IGF-I secretion to the annual rhythm of antler development Suttie et al., 1989.
As a prerequisite to test the hypothesis that the above mentioned growth factors are in- volved in processes such as spermatogenesis, cell proliferation and apoptosis in roe deer
testes, the expression of the corresponding genes needs to be investigated and was there- fore analysed using the reverse transcriptase polymerase chain reaction RT-PCR with the
subsequent comparison of results of the periods before, during and after the rut.
2. Materials and methods
