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Miller A, Jentz E, Duncan C, Merriman D. Progestogen metabolites for use in pregnancy monitoring of 13-lined ground squirrels ( Ictidomys tridecemlineatus). REPRODUCTION AND FERTILITY 2021; 2:81-88. [PMID: 35128444 PMCID: PMC8812425 DOI: 10.1530/raf-20-0071] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2021] [Accepted: 03/18/2021] [Indexed: 01/31/2023] Open
Abstract
13-lined ground squirrels (TLGS; Ictidomys tridecemlineatus) are small, omnivorous, fossorial, hibernating sciurids. TLGS are seasonal induced ovulators, with a ~28-day gestation period. The main goal of this study was to ascertain whether enzyme-linked immunosorbent assay (ELISA) of TLGS fecal samples can be used to non-invasively detect pregnancy. Competitive ELISAs for progestogen metabolites were conducted on feces collected from a group of (n =13) females. Feces were collected thrice weekly during the breeding season and frozen for subsequent analysis. Competitive ELISAs were run using progesterone kits ), setting data against seven different time-points between hibernation, emergence, and litter birthdate. Eleven females produced litters. ELISA data from the (n = 2) non-pregnant females demonstrated no rise in progestogen metabolites at any point over 28 days. In contrast, data from the (n = 11) pregnant females all demonstrated a pronounced rise in progestogen metabolites, with most animals displaying progesterone withdrawal in the final week of gestation. A >20-fold rise in progestogen metabolite was observed halfway through gestation (P < 005). Analysis on litter size and progestogen metabolite concentration showed no significant correlation (r2 = -0.615). Initial correlation analysis done on sex ratio of litters vs progestogen metabolites showed no significant effect of progesterone on sex ratios (males: r2 = -0.772, females: r2 = 0.375). This work demonstrated that TLGS also undergo progesterone withdrawal about a week before parturition. We have ascertained that a commercially available progesterone assay kit can detect a significant elevation in progestogen metabolites in this species about halfway through gestation. LAY SUMMARY This research was conducted to discover whether pregnancy prediction is possible in female 13-lined ground squirrels (TLGS; a small hibernating ground squirrel named for their number of stripes). Pregnancy status in this species, we postulated, could be anticipated by generating profiles for individuals via a non-invasive technique known as fecal endocrine hormone profiling. Fecal samples were collected from 13 females thrice weekly for 4 weeks post-hibernation in the breeding season of 2016. Fecal samples were then processed and run through an assay known as an ELISA giving concentrations of hormone metabolites excreted through feces. We then set these samples against time points to develop a profile for each female. We have ascertained that elevated progesterone (potential pregnancy) can be detected by a commercially available assay kit. Understanding hormone patterns in animals gives researchers a better idea of best husbandry practices, including breeding in managed care.
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Affiliation(s)
- Amy Miller
- Department of Biology, University of Wisconsin Oshkosh, Oshkosh, Wisconsin, USA,Correspondence should be addressed to A Miller:
| | - Elainna Jentz
- Department of Biology, University of Wisconsin Oshkosh, Oshkosh, Wisconsin, USA
| | - Cassandra Duncan
- Department of Biology, University of Wisconsin Oshkosh, Oshkosh, Wisconsin, USA
| | - Dana Merriman
- Department of Biology, University of Wisconsin Oshkosh, Oshkosh, Wisconsin, USA
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Edwards PD, Boonstra R. Coping with pregnancy after 9months in the dark: Post-hibernation buffering of high maternal stress in arctic ground squirrels. Gen Comp Endocrinol 2016; 232:1-6. [PMID: 26555380 DOI: 10.1016/j.ygcen.2015.11.004] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/12/2015] [Revised: 10/08/2015] [Accepted: 11/06/2015] [Indexed: 11/29/2022]
Abstract
Pregnancy and lactation are key times in the life of female mammals when energetic resources must be brought to bear to produce and nurture offspring. Changes in glucocorticoid (GC) levels are central to this objective, due to their roles in modulating development and physiology and in mediating energetic tradeoffs. We examined GC changes over reproduction in a species living in a harsh seasonal environment: the arctic ground squirrel (Urocitellus parryii). Females become pregnant immediately after emerging from a ∼9month hibernation, and then must begin this pregnancy during an additional month of freezing temperatures and limited food availability. We measured plasma levels of total cortisol, corticosteroid-binding globulin (CBG), and free cortisol in unstressed females at three stages: not-visibly pregnant, visibly pregnant, and lactating. Total cortisol levels were similar in all stages, but CBG levels increased 4-fold from the not-visibly pregnant stage to visibly pregnant and lactating stage. As a result, the free cortisol fraction declined from 51% of total cortisol when females were not-visibly pregnant to only 5% when they were visibly pregnant (remaining low and stable throughout pregnancy) and 10% when they were lactating. This pattern is markedly different from that seen in other mammals, where 10% or less of GCs are free and these tend to increase during gestation. We postulate that the high free cortisol just prior to visible pregnancy is a seasonal adaptation relating either to the pronounced physiological changes the female must undergo after emerging from hibernation and immediately getting pregnant, or to the mobilization of body reserves for energy to permit pregnancy, or both. Thereafter, high CBG levels may shield the developing offspring from the negative effects of cortisol overexposure.
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Affiliation(s)
- Phoebe D Edwards
- Centre for the Neurobiology of Stress, Department of Biological Sciences, University of Toronto Scarborough, Toronto, Ontario M1C 1A4, Canada.
| | - Rudy Boonstra
- Centre for the Neurobiology of Stress, Department of Biological Sciences, University of Toronto Scarborough, Toronto, Ontario M1C 1A4, Canada.
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Waterman J, Macklin G, Enright C. Sex-biased parasitism in Richardson’s ground squirrels (Urocitellus richardsonii) depends on the parasite examined. CAN J ZOOL 2014. [DOI: 10.1139/cjz-2013-0151] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Sex-biased parasitism is found in many species, but the skew to one sex or the other varies and is most likely due to differences in host and parasite behaviour and the intensity of sexual selection. We examined sex-biased parasitism in Richardson’s ground squirrels (Urocitellus richardsonii (Sabine, 1822)) and hypothesized that males would be more heavily parasitized than females, as they are larger, have larger home ranges, and display high aggression and fighting during the short mating season, suggesting that they may trade off investment in immunity for higher investment in reproduction. Squirrels were caught during the mating season and examined for endoparasites and ectoparasites. Body mass, condition, and immune measures were recorded. Males had higher nematode prevalence and abundance, whereas females had higher flea prevalence. Males also had lower lymphocytes than females, as well as higher neutrophil to lymphocyte ratios. Females had higher eosinophils and they were in poorer body condition than males. The higher endoparasite loads in males suggests that they may be trading off immunity, whereas higher flea prevalence in females may be due to differences in sociality between the sexes. Our study demonstrates the importance of examining multiple parasite types to understand the factors influencing sex-biased parasitism.
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Affiliation(s)
- J.M. Waterman
- Department of Biology, University of Manitoba, Winnipeg, MB R3T 2N2, Canada
| | - G.F. Macklin
- Department of Biology, University of Manitoba, Winnipeg, MB R3T 2N2, Canada
| | - C. Enright
- Assiniboine Park Zoo, 2595 Roblin Boulevard, Winnipeg, MB R3R 0B8, Canada
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Raveh S, Heg D, Viblanc VA, Coltman DW, Gorrell JC, Dobson FS, Balmer A, Neuhaus P. Male reproductive tactics to increase paternity in the polygynandrous Columbian ground squirrel (Urocitellus columbianus). Behav Ecol Sociobiol 2010. [DOI: 10.1007/s00265-010-1071-4] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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Bouchie L, Bennett NC, Jackson T, Waterman JM. ARE CAPE GROUND SQUIRRELS (XERUS INAURIS) INDUCED OR SPONTANEOUS OVULATORS? J Mammal 2006. [DOI: 10.1644/04-mamm-a-192r1.1] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
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Millesi E, Huber S, Pieta K, Walzl M, Arnold W, Dittami JP. Estrus and estrogen changes in mated and unmated free-living European ground squirrels. Horm Behav 2000; 37:190-7. [PMID: 10868482 DOI: 10.1006/hbeh.2000.1574] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The course of behavioral and vaginal estrus and patterns of circulating estrogens were followed in free-living European ground squirrels (Spermophilus citellus) after their emergence from hibernation. Normally mating females were compared to a second group in an area where males had been removed from the population before female emergence. Both groups showed vaginal estrus, but the patterns differed. Mating shortened vaginal estrus to a 3-day period compared to 8 days in unmated females. The extent (cell number) of cell cornification during estrus and the cellular components (percentage distribution) of metestrus did not differ between the two groups. Females in the area without males had significantly higher estrogen levels during estrus and metestrus compared to those in the control area. European ground squirrels were found to be monestrous, as none of the unmated females reentered estrus after metor diestrus was detected. The prolongation of vaginal estrus in unmated females can be viewed as either a physiological inevitability or an adaptation to low mate availability. The extension is still relatively short compared to other sciurid species and perhaps a product of constraints producing a strict time frame for reproduction.
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Affiliation(s)
- E Millesi
- Institute of Zoology, University of Vienna, Austria.
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Schwagmeyer P, Foltz D. Factors affecting the outcome of sperm competition in thirteen-lined ground squirrels. Anim Behav 1990. [DOI: 10.1016/s0003-3472(05)80735-3] [Citation(s) in RCA: 28] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
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Foreman D, Garris D. Plasma progesterone levels and corpus luteum morphology in the female prairie dog (Cynomys ludovicianus). Gen Comp Endocrinol 1984; 55:315-22. [PMID: 6541173 DOI: 10.1016/0016-6480(84)90117-5] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Plasma progesterone levels in female prairie dogs were determined by a radioimmunoassay specific for progesterone. Plasma progesterone levels were determined in samples taken before estrus, at estrus, during the luteal phase, and during anestrus from females maintained all year in the laboratory. Progesterone levels were also determined in plasma samples taken in the laboratory from two pregnant and three postparturient females captured in the field. Progesterone levels were low before estrus and continued low during estrus. They rose on the first week after estrus to 0.8 ng/ml or above and continued at or above this level for 9-14 weeks following estrus. Gestation in prairie dogs is 35 days in this species. Progesterone levels of three postparturient females were above 1.0 ng/ml for 7 weeks after their arrival in the laboratory. These females all had uterine scars showing that they had delivered their litters before they were captured. Two females were determined to be pregnant at the time of their capture. These females later reabsorbed their fetuses (determined by laparotomy). Progesterone values of samples from these females were all above 1.0 ng/ml except for one low value in one female which occurred 3 weeks after her capture and after reabsorption of her fetuses was in progress. The cells of the corpus lutea (CL) of nonpregnant, pregnant, and postparturient females had well-developed rings of cytoplasmic basophilia but as the CL regressed this pattern became disorganized and disappeared. The function of this basophilia is not known. The long luteal phase found in female prairie dogs is compared to those found in other species of mammals. This is the first annually breeding rodent reported to have a longer luteal phase that the period of gestation.
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Schwagmeyer PL, Brown CH. Factors affecting male-male competition in thirteen-lined ground squirrels. Behav Ecol Sociobiol 1983. [DOI: 10.1007/bf00295069] [Citation(s) in RCA: 41] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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Foreman D. Structural and functional homologies of the accessory reproductive glands of two species of sciurids, Cynomys ludovicianus and Citellus tridecemlineatus. Anat Rec (Hoboken) 1974; 180:331-9. [PMID: 4418748 DOI: 10.1002/ar.1091800207] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
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MCKEEVER S. Seasonal changes in body weight, reproductive organs, pituitary, adrenal glands, thyroid gland, and spleen of the belding ground squirrel (Citellus beldingi). ACTA ACUST UNITED AC 1963; 113:153-73. [PMID: 14042503 DOI: 10.1002/aja.1001130111] [Citation(s) in RCA: 23] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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ZANDER J. [The elimination of free corticoids in various functional states in women. I. Elimination in the menstrual cycle]. J Mol Med (Berl) 1953; 31:504-7. [PMID: 13085707 DOI: 10.1007/bf01477583] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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MILLER MR. Experimental alteration of the adrenal histology of the urodele amphibian, Triturus torosus. THE ANATOMICAL RECORD 1953; 116:205-25. [PMID: 13065755 DOI: 10.1002/ar.1091160208] [Citation(s) in RCA: 22] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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BURR JH, DAVIES JI. The vascular system of the rabbit ovary and its relationship to ovulation. THE ANATOMICAL RECORD 1951; 111:273-97. [PMID: 12976703 DOI: 10.1002/ar.1091110302] [Citation(s) in RCA: 57] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
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HANSSON ARTUR. THE PHYSIOLOGY OF REPRODUCTION IN MINK (MUSTELA VISON, SCHREB.) WITH SPECIAL REFERENCE TO DELAYED IMPLANTATION. ACTA ZOOL-STOCKHOLM 1947. [DOI: 10.1111/j.1463-6395.1947.tb00023.x] [Citation(s) in RCA: 139] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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Formation and growth of adrenocortical-like tissue in the ovaries of the adrenalectomized ground squirrel. ACTA ACUST UNITED AC 1944. [DOI: 10.1002/ar.1090890104] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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Wells LJ, Overholser MD. Effects of estrogen on the genital tract and urethra of anestrous female ground squirrels. Anat Rec (Hoboken) 1940. [DOI: 10.1002/ar.1090780106] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
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Dawson AB, Friedgood HB. The time and sequence of preovulatory changes in the cat ovary after mating or mechanical stimulation of the cervix uteri. ACTA ACUST UNITED AC 1940. [DOI: 10.1002/ar.1090760405] [Citation(s) in RCA: 34] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
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Pliske EC. The follicular cycle in the sexually mature thirteen-lined ground squirrel (Citellus tridecemlineatus Mitch.). J Morphol 1938. [DOI: 10.1002/jmor.1050630205] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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