Seasonal changes in the testes and accessory reproductive organs and seasonal and circadian changes in plasma testosterone concentrations in the male grey squirrel (Sciurus carolinensis)

1985 ◽  
Vol 59 (1) ◽  
pp. 15-23 ◽  
Author(s):  
G.E. Webley ◽  
G.S. Pope ◽  
Elizabeth Johnson
Keyword(s):  
Seasonal Changes ◽  
Reproductive Organs ◽  
Plasma Testosterone ◽  
Sciurus Carolinensis ◽  
Grey Squirrel ◽  
Circadian Changes

XIII.—Cytological Studies on the Reproductive Organs. Chromosome Behaviour in the Male Grey Squirrel (Sciurus carolinensis leucotus)

1937 ◽  
Vol 56 ◽  
pp. 196-209 ◽  
Author(s):  
P. C. Koller
Keyword(s):  
Reproductive Organs ◽  
Economic Importance ◽  
Sciurus Carolinensis ◽  
Chromosome Behaviour ◽  
American Continent ◽  
Grey Squirrel ◽  
Histological Changes ◽  
North American Continent ◽  
The North ◽  
Great Economic Importance

The grey squirrel (Sciurus carolinensis leucotus Gapper), which is a native of the North American continent, was introduced into England and Scotland quite recently and soon became of great economic importance in these countries. In his very excellent monograph, Middleton (1930) states that both sexes of the grey squirrel show diminished activity during the winter and while they do not hibernate in the true sense of the word, they probably sleep if the weather is severe. The breeding habits of the female were studied by Deanesly and Parkes (1933), who ascertained that the female definitely has a period of anœstrus during which the reproductive organs are atrophic. In the male, however, fully functional testes were found throughout the year (Allanson, 1933), and there were no histological changes which would indicate a regular period of quiescence.

METABOLISM OF ANDROGENS BY THE ACTIVE AND INACTIVE PROSTATE GLAND, AND THE SEASONAL CHANGES IN SYSTEMIC ANDROGEN LEVELS IN THE GREY SQUIRREL (SCIURUS CAROLINENSIS GMELIN)

1981 ◽  
Vol 88 (3) ◽  
pp. 381-NP ◽  
Author(s):  
A. A. SIWELA ◽  
W. H. TAM
Keyword(s):  
Breeding Season ◽  
Seasonal Changes ◽  
Subcellular Fraction ◽  
Prostate Gland ◽  
Secretory Activity ◽  
Sciurus Carolinensis ◽  
Grey Squirrel ◽  
Androgen Level ◽  
Grey Squirrels ◽  
Androgen Levels

The nuclear and cytoplasmic fractions derived from the actively secretory and inactive prostate of adult grey squirrels were incubated with radioactive testosterone and androstenedione. Testosterone was metabolized first to 5α-dihydrotestosterone and then 5 α-androstane-3α(β), 17β-diols. Testosterone could also be transformed into androstenedione and then to androsterone, but no 5α-dihydrotestosterone or diols could be synthesized from this pathway. Neither subcellular fraction of the inactive, non-secretory prostate could produce 5α-androstane-3α(β),17β-diols from testosterone either in the absence or presence of exogenous NADPH. The synthesis of androstenedione and 5α-dihydrotestosterone by the nuclear and cytoplasmic fractions of the inactive gland were significantly increased compared to that in fractions of the active prostate. The increase was unaffected by exogenous NADPH. The concentration of androgen (testosterone plus 5α-dihydrotestosterone) in systemic plasma was highest in December, the beginning of the breeding season. For the remainder of the breeding season, the androgen level was similar to that found in the non-breeding season. It is suggested that formation of 5α-androstane-3α(β),17β-diols was associated with the secretory activity of the prostate. The failure of the inactive prostate to synthesize these diols during sexual quiescence might be a means of ensuring the inactivity of the prostate.

scholarly journals Part V. Changes in the reproductive organs of the male grey squirrel (Sciurus carolinensis)

1932 ◽  
Vol 222 (483-493) ◽  
pp. 79-96 ◽  
Keyword(s):  
Sexual Activity ◽  
Seasonal Cycle ◽  
Great Majority ◽  
Reproductive Activity ◽  
Reproductive Organs ◽  
Severe Weather ◽  
Sciurus Carolinensis ◽  
Initial Growth ◽  
General Activity ◽  
Grey Squirrel

I. Introduction. Both sexes of the grey squirrel show diminished general activity during the winter months and, while there is no true hibernation, squirrels probably sleep during severe weather (Middleton, 1930). In Part IV, Deanesly and Parkes show that sexual activity in the female is limited to the spring and summer, the reproductive organs being quiescent throughout the rest of the year. In view of these facts it seemed probable that the male squirrel would also show seasonal reproductive activity. The present paper deals with an investigation into this question and also with a study of the correlation between the size of the testes and that of the accessory reproductive organs. From the material it is evident that there is no regular seasonal cycle in the reproductive organs of the male squirrel, which considered as a species, therefore, has no “ anoestrus.” The possibility that individual males may experience temporary periods of inactivity cannot be excluded, but there is no doubt that the great majority of inactive animals are prepubertal. Therefore size changes in the testis, in its constituent parts, and in the accessory organs, are considered to represent initial growth

scholarly journals Novel combination of CRISPR-based gene drives eliminates resistance and localises spread

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Nicky R. Faber ◽  
Gus R. McFarlane ◽  
R. Chris Gaynor ◽  
Ivan Pocrnic ◽  
C. Bruce A. Whitelaw ◽  
...  
Keyword(s):  
Driving Forces ◽  
Spatial Models ◽  
Cost Effective ◽  
Biodiversity Loss ◽  
Invasive Pest ◽  
Economic Losses ◽  
Sciurus Carolinensis ◽  
Gene Drive ◽  
Grey Squirrel ◽  
Gene Drives

AbstractInvasive species are among the major driving forces behind biodiversity loss. Gene drive technology may offer a humane, efficient and cost-effective method of control. For safe and effective deployment it is vital that a gene drive is both self-limiting and can overcome evolutionary resistance. We present HD-ClvR in this modelling study, a novel combination of CRISPR-based gene drives that eliminates resistance and localises spread. As a case study, we model HD-ClvR in the grey squirrel (Sciurus carolinensis), which is an invasive pest in the UK and responsible for both biodiversity and economic losses. HD-ClvR combats resistance allele formation by combining a homing gene drive with a cleave-and-rescue gene drive. The inclusion of a self-limiting daisyfield gene drive allows for controllable localisation based on animal supplementation. We use both randomly mating and spatial models to simulate this strategy. Our findings show that HD-ClvR could effectively control a targeted grey squirrel population, with little risk to other populations. HD-ClvR offers an efficient, self-limiting and controllable gene drive for managing invasive pests.

scholarly journals The genome sequence of the eastern grey squirrel, Sciurus carolinensis Gmelin, 1788

2020 ◽  
Vol 5 ◽  
pp. 27
Author(s):  
Dan Mead ◽  
Kathryn Fingland ◽  
Rachel Cripps ◽  
Roberto Portela Miguez ◽  
Michelle Smith ◽  
...  
Keyword(s):  
Genome Sequence ◽  
Sex Chromosomes ◽  
Genome Assembly ◽  
Sciurus Carolinensis ◽  
Grey Squirrel ◽  
Individual Male ◽  
A Genome

We present a genome assembly from an individual male Sciurus carolinensis (the eastern grey squirrel; Vertebrata; Mammalia; Eutheria; Rodentia; Sciuridae). The genome sequence is 2.82 gigabases in span. The majority of the assembly (92.3%) is scaffolded into 21 chromosomal-level scaffolds, with both X and Y sex chromosomes assembled.

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