36 research outputs found
Methodological considerations in the analysis of fecal glucocorticoid metabolites in tufted capuchins (Cebus apella)
Analysis of fecal glucocorticoid (GC) metabolites has recently become the standard method to monitor adrenocortical activity in primates noninvasively. However, given variation in the production, metabolism, and excretion of GCs across species and even between sexes, there are no standard methods that are universally applicable. In particular, it is important to validate assays intended to measure GC production, test extraction and storage procedures, and consider the time course of GC metabolite excretion relative to the production and circulation of the native hormones. This study examines these four methodological aspects of fecal GC metabolite analysis in tufted capuchins (Cebus apella). Specifically, we conducted an adrenocorticotrophic hormone (ACTH) challenge on one male and one female capuchin to test the validity of four GC enzyme immunoassays (EIAs) and document the time course characterizing GC me- tabolite excretion in this species. In addition, we compare a common field-friendly technique for extracting fecal GC metabolites to an established laboratory extraction methodology and test for effects of storing “field extracts” for up to 1 yr. Results suggest that a corticosterone EIA is most sensitive to changes in GC production, provides reliable measures when extracted according to the field method, and measures GC metabolites which remain highly stable after even 12 mo of storage. Further, the time course of GC metabolite excretion is shorter than that described yet for any primate taxa. These results provide guidelines for studies of GCs in tufted capuchins, and underscore the importance of validating methods for fecal hormone analysis for each species of interest
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The rise of linear borders in world politics
This article argues that the dominance of precise, linear borders as an ideal in the demarcation of territory is an outcome of a relatively recent and ongoing historical process, and that this process has had important effects on international politics since circa 1900. Existing accounts of the origins of territorial sovereignty are in wide disagreement largely because they fail to specify the relationship between territory and borders, often conflating the two concepts. I outline a history of the linearization of borders which is separate from that of territorial sovereignty, having a very different timeline and featuring different actors, and offer an explanation for the dominance of this universalizing system of managing and demarcating space, based on the concept of rationalization. Finally I describe two broad ways in which linearizing borders has affected international politics, by making space divisible in new ways, and underpinning hierarchies by altering the distribution of geographical knowledge resources
Neutrophils in cancer: neutral no more
Neutrophils are indispensable antagonists of microbial infection and facilitators of wound healing. In the cancer setting, a newfound appreciation for neutrophils has come into view. The traditionally held belief that neutrophils are inert bystanders is being challenged by the recent literature. Emerging evidence indicates that tumours manipulate neutrophils, sometimes early in their differentiation process, to create diverse phenotypic and functional polarization states able to alter tumour behaviour. In this Review, we discuss the involvement of neutrophils in cancer initiation and progression, and their potential as clinical biomarkers and therapeutic targets
Reproductive endocrinology of zoo-housed aardwolves
Knowledge regarding the relationship between endocrine parameters and reproductive activity
can offer important insights into how social and environmental factors influence the
reproductive success of mammals. Although components of both the physical and social
environment affect endocrine regulation of reproduction, less is understood about the
potential role of interactions between different endocrine axes on reproductive activity. We
evaluated temporal patterns of reproductive and adrenocortical steroids in two male and three
female aardwolves (Proteles cristata) housed in captivity at Brookfield Zoo, Chicago, USA.
We found seasonal variation in faecal androgens, estrogens, and progestagens, which provide
support for previous observations of the aardwolf as a seasonal breeder. However, the timing
of peak endocrine activity did not correspond to observations from wild populations. Our
interpretation is that this discrepancy is caused by photoperiodic regulation of reproductive
activity. We found a positive relationship between faecal androgens and faecal glucocorticoid
metabolites in males and a positive relationship between faecal estrogens and faecal
glucocorticoid metabolites in females when housed with conspecifics but not when housed
alone. We also found a positive but asymptotic relationship between faecal progestagens and
faecal glucocorticoid metabolites. We argue that these observations indicate a potential effect
of reproductive endocrine activity on the hypothalamic-pituitary adrenal axis, which could
result in interesting physiological trade-offs in male reproductive tactics and female prepartum
maternal investment because of the negative effects of long-term glucocorticoid
elevation on reproductive performance. Finally, our results suggest that social and
environmental factors interact in regulating many aspects of endocrine fluctuations in this
mostly solitary species.D. Marneweck, F. Dalerum and A. Ganswindt were supported by the National Research Foundation of South Africa, and F. Dalerum and A. Ganswindt were further supported by research fellowships from University of Pretoria.http://acta.zbs.bialowieza.pl/hb2013ab201
Female reproductive activity and its endocrine correlates in the African lesser bushbaby, Galago moholi
Steroid hormones play an important role in
female reproductive physiology and behaviour and are
often used to monitor important female reproductive events.
However, such studies are often attempted on captive populations
alone, delivering limited data. One such example
is the African lesser bushbaby, Galago moholi, for which
contradicting observational data exist between captive and
free-ranging populations, while hormonal analyses have
only been obtained from a single captive population. To
extend and rectify the limited information, we monitored
faecal progestagen and oestrogen metabolite levels across
various important life history stages of both captive and
free-ranging G. moholi. We additionally recorded changes
in vaginal state as well as the occurrence of reproductive
and aggressive behaviour throughout the study. Data from
our captive population revealed an ovarian cycle length of
33.44 ± 0.59 days (mean ± SD), with follicular and luteal
phases of 14.2 ± 1.0 and 19.1 ± 1.5 days, respectively,
and an average pregnancy length of 128 ± 3.3 days. The initiation of female reproductive activity was closely linked
to an oestrus-related increase in faecal oestrogen metabolite
levels. Four of the seven captive females monitored in
our study conceived during the May mating period, with
one additional female fertilised in September, supporting
the idea that the September mating period functions as a
back-up for female G. moholi. Identified benchmark faecal
progestagen metabolite levels (non-pregnant: >1 μg/g dry
weight (DW), pregnant: >9 μg/g DW) should help researchers
to determine pregnancy status of randomly wild-caught
females in even a cross-sectional study setup.Deutsche Forschungsgemeinschaft (DFG; DA 1031/3-1/2) and the DST-NRF SarchI Chair of Mammal Behavioural Ecology and Physiology.http://link.springer.com/journal/3602017-02-28hb201