Publications by authors named "S Trombley"

12 Publications

  • Page 1 of 1

Demography of the salt marsh harvest mouse () and associated rodents in tidal and managed wetlands.

J Mammal 2020 Feb 30;101(1):129-142. Epub 2019 Nov 30.

Department of Wildlife, Fish and Conservation Biology, University of California, Davis, Davis, CA, USA.

Suisun Marsh (Solano County, California) is the largest contiguous marsh remaining on the West Coast of the United States, and makes up approximately 10% of the wetlands remaining in the San Francisco Estuary. Suisun Marsh has been safeguarded from development through the operation of over 100 privately owned waterfowl hunting clubs, which manage for diked waterfowl habitat. However, this management-and the subsequent loss of tidal influence-has been considered harmful for some species, including the endangered salt marsh harvest mouse (SMHM; ). To determine the value of tidal wetlands relative to those managed for waterfowl, we performed periodic surveys for rodents in managed and tidal wetlands over 5 years, and used capture-mark-recapture analyses to estimate demographic parameters and abundance for the three most common rodents-the northern SMHM (), the western harvest mouse (a sympatric native species; , WHM), and the house mouse (a sympatric invasive species; ). Wetland type had no effect on detection, temporary emigration, or survival for any of these species. However, fecundity and population growth for all three species were affected by an interaction of season and wetland type, although none of these parameters was consistently superior in either habitat type. Estimated abundance of SMHM and was similar in both wetland types, whereas WHM were more abundant in managed wetlands. Salt marsh harvest mice also showed no affinity for any microhabitat characteristics associated with tidal wetlands. Managed wetlands in Suisun Marsh support SMHM and equally, and abundances of WHM were greater than in tidal wetlands, suggesting managed wetlands may be superior in terms of supporting native rodents. As climate change and sea level rise are predicted to threaten coastal marshes, these results suggest the recovery strategy for SMHM could incorporate managed wetlands.
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http://dx.doi.org/10.1093/jmammal/gyz183DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7035210PMC
February 2020

Effects of androgens on the leptin system in immature male Atlantic salmon parr.

Gen Comp Endocrinol 2018 02 19;257:122-129. Epub 2017 Aug 19.

Department of Organismal Biology, Comparative Physiology, Evolutionary Biology Centre, Uppsala University, SE-752 36 Uppsala, Sweden. Electronic address:

Leptin modulates all levels of the reproductive endocrine axis in mammals, and in turn, both leptin and the leptin receptor are regulated by sex steroids. The aim of this study was to investigate if sex steroids regulate the leptin system also in fish. Immature one-year old male Atlantic salmon parr were implanted with Silclear capsules that were either empty or filled with 11-ketoandrostenedione (11KA) or testosterone (T) and the effects of 35-days treatment were investigated on measures of maturation, gene expression of leptin (lepa1, lepa2), leptin receptor (lepra1) and circulating plasma leptin. Both 11-KA and T stimulated the reproductive axis by increasing testes weight and up-regulated pituitary lh-β mRNA levels and for T also fsh-β. T up-regulated transcription levels of lepa1 and lepra1 in the pituitary, while 11-KA had no effect. Leptin receptor expression in the testis was unaltered by either androgen. T up-regulated lepa1 mRNA levels significantly also in the liver, but had no effect on lepa2, and 11KA did not affect hepatic gene expression of either lepa1 or lepa2. Plasma leptin levels did not differ significantly between treatments. The results indicate that androgens regulate gene expression of leptin and the leptin receptor in different tissues in fish and that the effects of leptin might be tissue specific considering plasma levels remained unaltered. Overall, the results suggest a role for leptin in fish reproduction, where sex steroids are able to regulate components of the leptin system differentially in liver and important tissues of the reproductive axis.
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http://dx.doi.org/10.1016/j.ygcen.2017.08.014DOI Listing
February 2018

Sex steroids stimulate leptin gene expression in Atlantic salmon parr hepatocytes in vitro.

Gen Comp Endocrinol 2015 Sep 30;221:156-64. Epub 2015 Jan 30.

Department of Organismal Biology, Comparative Physiology, Evolutionary Biology Centre, Uppsala University, SE-752 36 Uppsala, Sweden. Electronic address:

In mammals, leptin plays an important role in puberty and reproduction and leptin is regulated by sex steroids. Elevated leptin levels have been associated with sexual maturation in some teleosts such as Atlantic salmon. In the present study, primary cultures of Atlantic salmon hepatocytes were used to investigate the direct effects of different sex steroids on expression of the two salmon leptin-a genes, lepa1 and lepa2. Testosterone (T) stimulated both lepa1 and lepa2 in a dose dependent manner after four days of incubation. The stimulatory effect of T on leptin expression was not prevented by co-incubation with the aromatase inhibitor fadrozole, indicating a direct androgen effect on transcription. The non-aromatizable androgen 11-ketotestosterone (11-KT), which is the main androgen in fish, was generally slightly less potent than T in stimulating lepa1 and lepa2. The strongest stimulatory response was seen for 17β-estradiol (E2). E2 treatment significantly up-regulated lepa1 and lepa2 gene expression at doses of 10nM and 1nM for each gene, respectively. Lepa1, but not lepa2, was stimulated by T and 11-KT in immature male and immature female parr, while E2 stimulated expression of both genes. The sensitivity to sex steroid stimulation differed in maturing males compared to immature. In maturing males, the androgens and E2 stimulated lepa2 but not lepa1, while in immature males, the androgens and E2 stimulated lepa1, but only E2 stimulated lepa2. The differential response of the two leptin paralogues to the sex steroids suggests differences in regulation of the two leptin genes during maturation. Altogether, these results indicate that leptin expression in Atlantic salmon hepatocytes is directly regulated at the transcriptional level by the main teleost androgens and an estrogen, and that the response might depend on the developmental stage of the fish.
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http://dx.doi.org/10.1016/j.ygcen.2015.01.015DOI Listing
September 2015

Regulation of the seasonal leptin and leptin receptor expression profile during early sexual maturation and feed restriction in male Atlantic salmon, Salmo salar L., parr.

Gen Comp Endocrinol 2014 Aug 10;204:60-70. Epub 2014 May 10.

Department of Organismal Biology, Comparative Physiology, Evolutionary Biology Centre, Uppsala University, SE-752 36 Uppsala, Sweden. Electronic address:

In mammals, leptin acts as an adiposity signal and is a crucial link between nutritional status and the reproductive axis. So far the link between leptin and energy balance during sexual maturation in teleosts has been poorly investigated. In this study, seasonal gene expression changes in two leptin genes (lepa1 and lepa2) and the leptin receptor were investigated during early sexual maturation in male Atlantic salmon parr under fully fed (control) and feed restricted conditions from April through September. Both Atlantic salmon lepa1 and lepa2 in the liver and lepr in the brain were significantly down-regulated in non-maturing control males in early spring, coinciding with the start of the growth and fat accumulation. In maturing control males, hepatic leptin expression increased during mid-spermatogenesis and lepa1 and lepa2 mRNA levels were up-regulated by 7.7 and 49 times respectively during final maturation. For the first time in a fish species, a significant up-regulation of lepr expression was observed in the testis throughout mid to late spermatogenesis. Feed restriction decreased the incidence of sexual maturation by 53% and highly up-regulated both leptin genes in the liver and the leptin receptor in the pituitary. This study shows that hepatic lepa1 and lepa2 expression and lepr expression in the testis is affected by early sexual maturation in male Atlantic salmon parr. Fast growth and high fat stores are associated with low leptin levels while feed restriction has a stimulatory effect on hepatic leptin and leptin receptor gene expression in the pituitary, suggesting a role for leptin other than that as an adiposity signal.
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http://dx.doi.org/10.1016/j.ygcen.2014.04.033DOI Listing
August 2014

The mating brain: early maturing sneaker males maintain investment into the brain also under fast body growth in Atlantic salmon ().

Evol Ecol 2014;28(6):1043-1055. Epub 2014 Jun 5.

Department of Animal Ecology, Evolutionary Biology Centre, Uppsala University, Norbyvägen 18D, 75236 Uppsala, Sweden ; Department of Zoology/Ethology, Stockholm University, 10691 Stockholm, Sweden.

It has been suggested that mating behaviours require high levels of cognitive ability. However, since investment into mating and the brain both are costly features, their relationship is likely characterized by energetic trade-offs. Empirical data on the subject remains equivocal. We investigated if early sexual maturation was associated with brain development in Atlantic salmon (), in which males can either stay in the river and sexually mature at a small size (sneaker males) or migrate to the sea and delay sexual maturation until they have grown much larger (anadromous males). Specifically, we tested how sexual maturation may induce plastic changes in brain development by rearing juveniles on either natural or ad libitum feeding levels. After their first season we compared brain size and brain region volumes across both types of male mating tactics and females. Body growth increased greatly across both male mating tactics and females during ad libitum feeding as compared to natural feeding levels. However, despite similar relative increases in body size, early maturing sneaker males maintained larger relative brain size during ad libitum feeding levels as compared to anadromous males and females. We also detected several differences in the relative size of separate brain regions across feeding treatments, sexes and mating strategies. For instance, the relative size of the cognitive centre of the brain, the telencephalon, was largest in sneaker males. Our data support that a large relative brain size is maintained in individuals that start reproduction early also during fast body growth. We propose that the cognitive demands during complex mating behaviours maintain a high level of investment into brain development in reproducing individuals.
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http://dx.doi.org/10.1007/s10682-014-9715-xDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4459551PMC
June 2014

Androgen feedback effects on LH and FSH, and photoperiodic control of reproduction in male three-spined sticklebacks, Gasterosteus aculeatus.

Gen Comp Endocrinol 2013 Feb 29;182:16-23. Epub 2012 Nov 29.

Department of Zoology, Stockholm University, S-106 91 Stockholm, Sweden.

Sexual maturation in the stickleback is controlled by photoperiod. The aim of this study was to find out whether changes in feedback effects exerted by sex steroids could mediate the photoperiodic effect, which is regarded to be of an all-or-nothing character. To that end, males were castrated and treated with different doses of testosterone (T) and in one experiment also with the aromatase inhibitor fadrozole (AI) and kept under different photoperiods. In control fish, long day (LD 16:8) stimulated maturation, associated with more hypertrophied kidneys (a secondary sexual character) and higher levels of pituitary lhb and fshb mRNA than under short day conditions (LD 8:16). Under LD 8:16, low doses of T suppressed both lhb and fshb mRNA levels. However, with the use of high doses of T and/or longer photoperiods the inhibitory effects on lhb and fshb mRNA levels became less clear or instead positive effects were observed. Under intermediate photoperiod conditions, the negative feedback effect of a low dose of T on fshb was more prominent with shorter photoperiods, whereas no such shift was observed for lhb mRNA. The inhibitory effect of the low dose of T on lhb mRNA levels under LD 8:16 was abolished by AI, whereas the stimulatory effect of the high dose of T was not. The negative feedback effects were more marked under short days than under long days, whereas positive feedback effects were more marked under long days. The suppression of both fshb and lhb mRNA levels by low androgen levels, especially under short days, may inhibit maturation completely unless a rise of androgens above threshold levels would allow complete maturation.
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http://dx.doi.org/10.1016/j.ygcen.2012.10.017DOI Listing
February 2013

Leptin in fish: possible role in sexual maturation in male Atlantic salmon.

Fish Physiol Biochem 2013 Feb 7;39(1):103-6. Epub 2012 Oct 7.

Department of Organismal Biology, Comparative Physiology, Evolutionary Biology Center, Uppsala University, Norbyvägen 18A, 752 36, Uppsala, Sweden.

Leptin plays an important role in energy homeostasis and reproductive function in mammals, while its function in fish is still poorly understood, especially its role in reproduction. In the present study, leptin gene expression and circulating leptin plasma levels were measured during sexual maturation in male Atlantic salmon parr. In maturing male salmon, higher hepatic leptin (lepa1) gene expression levels were observed during mid-spermatogenesis compared to immature fish. An upregulation of leptin during sexual maturation has also been observed in a few other teleost species. The physiological significance of elevated leptin levels during the maturational process in teleosts remains to be explored.
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http://dx.doi.org/10.1007/s10695-012-9731-0DOI Listing
February 2013

Schistocephalus solidus infections increase gonadotropins and gonadotropin releasing hormone (GnRH3) mRNA levels in the three-spined stickleback, Gasterosteus aculeatus.

Parasitol Int 2012 Sep 30;61(3):470-4. Epub 2012 Mar 30.

Department of Zoology, Stockholm University, S-106 91 Stockholm, Sweden.

Parasites often impair the reproduction of their hosts, one well known case being the cestode Schistocephalus solidus which is a common parasite in three-spined sticklebacks, Gasterosteus aculeatus. One of the possible ways that this could be exerted is by suppression on the brain-pituitary-gonadal (BPG) axis. In this study, mRNA levels of FSH-β and LH-β and of GnRH2 (cGnRH II) and GnRH3 (sGnRH) were measured via Q-PCR in infected and uninfected fish sampled from the field a few weeks before the onset of breeding. The pituitary mRNA levels of both FSH-β and LH-β were higher in infected males than in uninfected males. Also in females, FSH-β mRNA levels were higher in infected individuals than in others, whereas there was no significant difference found in LH-β expression. Brain mRNA levels of GnRH3 were higher in infected fish than in uninfected fish in both sexes, but no difference was found in GnRH2 mRNA levels. Thus, infection by S. solidus was able to alter the expressions not only of gonadotropins (GtHs), but also of GnRH which has not been observed previously. However, the effects are opposite to what should be expected if the parasite suppressed reproduction via actions on the brain-pituitary level. The gonads are perhaps more likely to be impaired by the parasites in other ways, and changed feedbacks on the BPG axis could then lead to the increases in GtHs and GnRH.
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http://dx.doi.org/10.1016/j.parint.2012.03.006DOI Listing
September 2012

Effects of long-term restricted feeding on plasma leptin, hepatic leptin expression and leptin receptor expression in juvenile Atlantic salmon (Salmo salar L.).

Gen Comp Endocrinol 2012 Jan 12;175(1):92-9. Epub 2011 Oct 12.

Evolutionary Biology Centre, Department of Organismal Biology/Comparative Physiology, Uppsala University, SE-752 36 Uppsala, Sweden.

Leptin is a pleiotropic hormone and plays a key role in body weight regulation, energy homeostasis and lipid store utilization in mammals. In this study, we investigated the effect of feed-restriction on leptin genes (lepa1 and lepa2), leptin receptor (lepr) gene expression and plasma leptin levels in juvenile Atlantic salmon parr. Feed restriction was performed from late April to mid-June, in order to gain insight into the role of the leptin system in energy balance regulation and adiposity in juvenile salmon. A significant increase in lepa1 expression as well as higher levels of plasma leptin was found in feed-restricted fish in June compared to fully fed controls, while lepa2 gene expression decreased in both groups during the treatment period. Lepa2 was, however significantly higher in the feed-restricted group in June. Leptin receptor expression was up regulated during the period of enhanced growth and lipid deposition in the fully fed control, indicating a seasonal effect on the receptor expression in the brain. Both lepa1 and lepa2 genes very mainly expressed in the liver in juvenile salmon, while lepr was expressed in the brain but showed also considerable expression in various peripheral tissues. The study provides evidence that the leptin system is sensitive to the metabolic status of the fish as both season and restricted feeding affect lepa1 and lepa2 gene expression in the liver and brain leptin receptor expression, however, for lepa1 expression and leptin plasma level in an opposite way as that observed in the mammalian system.
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http://dx.doi.org/10.1016/j.ygcen.2011.10.001DOI Listing
January 2012

Improved lactation with metoclopramide. A case report.

Clin Pediatr (Phila) 1993 Jan;32(1):53-7

Department of Pediatrics, University of Arizona Health Sciences Center, Tucson.

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http://dx.doi.org/10.1177/000992289303200111DOI Listing
January 1993

Information exchange.

Nurs Stand 1990 Jun;4(38):42

I am a district nurse- student, working in West Essex Health Authority.
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http://dx.doi.org/10.7748/ns.4.38.42.s40DOI Listing
June 1990

All that summer she was mad: Virginia Woolf and her doctors.

Authors:
S Trombley

Soc Soc Hist Med Bull (Lond) 1981 Jun;28:21-5

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June 1981