scholarly journals Flexibility in thermoregulatory physiology of two dunnarts, Sminthopsis macroura and Sminthopsis ooldea (Marsupialia; Dasyuridae)

2012 ◽  
Vol 215 (13) ◽  
pp. 2236-2246 ◽  
Author(s):  
S. Tomlinson ◽  
P. C. Withers ◽  
S. K. Maloney
Keyword(s):  
Sminthopsis Macroura

Vertebrate Remains in Pellets of the Barn Owl, Tyto Alba, From Planet Downs Station, South-Western Queensland.

1981 ◽  
Vol 8 (1) ◽  
pp. 181 ◽  
Author(s):  
A Valente
Keyword(s):  
Mus Musculus ◽  
Prey Item ◽  
Barn Owl ◽  
Tyto Alba ◽  
Sminthopsis Macroura

Vertebrate remains in a collection of barn owl (Tyto alba) pellets from south-western Queensland were largely those of mammals, including Rattus villosissimus, Mus musculus, Leggadina forresti, Planigale tenuirostris, Sminthopsis macroura and S. crassicaudata. R. villosissimus was the most common prey item. P. tenuirostris had not been recorded previously from the area. Other vertebrate remains included those of birds, lizards and frogs. Some insects were also found in the pellets.

scholarly journals Sensitivity of The Stripe-Faced Dunnart, Sminthopsis Macroura (Gould 1845), To The Phenyl Pyrazole Insecticide, Fipronil, Toxicological Signs And Implications For Pesticide Risk Assessments In Australia

2021 ◽  
Author(s):  
Paul Story ◽  
Lyn A Hinds ◽  
Steve Henry ◽  
Andrew C. Warden ◽  
Greg Dojchinov
Keyword(s):  
Lethal Dose ◽  
Risk Assessments ◽  
Eutherian Mammal ◽  
Oral Toxicity ◽  
Median Lethal Dose ◽  
Agricultural Pesticides ◽  
Sminthopsis Macroura ◽  
The Difference ◽  
Ld50 Value ◽  
Female Responses

Abstract A lack of toxicity data quantifying responses of Australian native mammals to agricultural pesticides prompted an investigation into the sensitivity of the stripe-faced dunnart, Sminthopsis macroura (Gould 1845) to the insecticide, fipronil (5-amino-3-cyano-1-(2,6-dichloro-4-trifluoromethylphenyl)-4-trifluoromethylsulfinyl pyrazole, CAS No. 120068-37-3). Using the Up-And-Down method for determining acute oral toxicity in mammals, derived by the Organisation for Economic Cooperation and Development (OECD), median lethal dose estimates of 990 mg kg− 1 (95% confidence interval (CI) = 580.7–4770.0 mg kg− 1) and 270.4 mg kg− 1 (95% CI = 0.0 - >20000.0 mg kg− 1) were resolved for male and female S. macroura respectively. The difference between median lethal dose estimates for males and females may have been influenced by the increased age of two female dunnarts. Further modelling of female responses to fipronil doses used the following assumptions: (a) death at 2000 mg kg− 1, (b) survival at 500 mg kg− 1 and (c) a differential response (both survival and death) at 990 mg kg− 1. This modelling revealed median lethal dose estimates for female S. macroura of 669.1 mg kg− 1 (95% CI = 550–990 mg kg− 1; assuming death at 990 mg kg− 1) and 990 mg kg− 1 (95% CI = 544.7–1470 mg kg− 1; assuming survival at 990 mg kg− 1). These median lethal dose estimates are 3–10-fold higher than the only available LD50 value for a similarly sized eutherian mammal, Mus musculus (L. 1758; 94 mg kg− 1) and that available for Rattus norvegicus (Birkenhout 1769; 97 mg kg− 1). Implications for pesticide risk assessments in Australia are discussed.

Daily changes in food availability, but not long-term unpredictability, determine daily torpor-bout occurrences and frequency in stripe-faced dunnarts (Sminthopsis macroura)

2015 ◽  
Vol 63 (1) ◽  
pp. 12 ◽  
Author(s):  
Alexandra M. Leslie ◽  
Mathew Stewart ◽  
Elizabeth Price ◽  
Adam J. Munn
Keyword(s):  
Food Availability ◽  
Control Period ◽  
Daily Torpor ◽  
Torpor Bout ◽  
Effect Of Food ◽  
Rapid Adjustment ◽  
Sminthopsis Macroura ◽  
Ad Libitum ◽  
Ad Libitum Intake ◽  
Ad Libitum Feeding

Daily torpor, a short-term reduction in body temperature and metabolism, is an energy-saving strategy that has been interpreted as an adaptation to unpredictable resource availability. However, the effect of food-supply variability on torpor, separately from consistent food restriction, remains largely unexamined. In this study, we investigated the effect of unpredictable food availability on torpor in stripe-faced dunnarts (Sminthopsis macroura). After a control period of ad libitum feeding, dunnarts were offered 65% of their average daily ad libitum intake over 31 days, either as a constant restriction (i.e. as equal amount of food offered each day) or as an unpredictable schedule of feed offered, varied daily as 0%, 30%, 60%, 100% or 130% of ad libitum. Both feeding groups had increased torpor-bout occurrences (as a proportion of all dunnarts on a given day) and torpor-bout frequency (average number of bouts each day) when on a restricted diet compared with ad libitum feeding, but torpor frequency did not differ between the consistently restricted and unpredictably restricted groups. Most importantly, torpor occurrence and daily bout frequency by the unpredictably restricted group appeared to change in direct association with the amount of food offered on each day; torpor frequency was higher on days of low food availability. Our data do not support the interpretation that torpor is a response to unpredictable food availability per se, but rather that torpor allowed a rapid adjustment of energy expenditure to manage daily fluctuations in food availability.

Torpor in the Carnivorous Marsupial Sminthopsis macroura: Effects of Food Quality and Quantity

2000 ◽  
pp. 127-137 ◽  
Author(s):  
Kerry W. Withers ◽  
Debra H. White ◽  
John Billingsley
Keyword(s):  
Food Quality ◽  
Sminthopsis Macroura ◽  
Carnivorous Marsupial

scholarly journals Induced ovulation, mating success and embryonic development in the stripe-faced dunnart, Sminthopsis macroura

Reproduction ◽  
2001 ◽  
pp. 777-783 ◽  
Author(s):  
DE Hickford ◽  
NE Merry ◽  
MH Johnson ◽  
L Selwood
Keyword(s):  
Oocyte Maturation ◽  
Mating Success ◽  
Luteal Phase ◽  
Intermediate Phase ◽  
Corpora Lutea ◽  
Induced Ovulation ◽  
Ovarian Histology ◽  
Sminthopsis Macroura ◽  
Combined Data ◽  
Natural Cycles

Induced ovulation resulting in normal embryos is rare in marsupials. In this study natural and induced ovulations were compared in mature Sminthopsis macroura (n = 122). Comparison of maturation of preovulatory oocytes by ovarian histology and examination of oocytes removed from developing follicles in 12 ovaries of 23 animals receiving 0.058 iu equine serum gonadotrophin (eSG) g(-1) with ovaries of 12 animals undergoing natural cycles showed that oocyte maturation was significantly more irregular when it was induced (P < 0.001). Postovulatory stages were examined by estimating the number of eggs ovulated from ovarian histology, and by counting oviduct and uterine contents recovered after ovulation. S. macroura receiving 0.087 iu eSG g(-1) (n = 34), administered as one (n = 17) or two (n = 17) injections, were significantly (P < 0.05) more likely to ovulate (74%), mate (80%) and have conceptuses (66%) than were animals receiving 0.058 iu eSG g(-1) (12, 53 and 0%, respectively) (n = 17), and the values were similar to those in animals (n = 36) undergoing natural cycles (100, 81 and 56%, respectively). Induced ovulation using 0.087 iu eSG g(-1) yielded significantly (P < 0.05) more oocytes per ovary (20.8 +/- 8.5; combined data) than did ovulation in animals undergoing natural cycles (13.7 +/- 3.2) (ANOVA, t test). The responses of animals induced in different phases of the oestrous cycle with 0.087 iu eSG g(-1) were not significantly different (ANOVA) with respect to the number of corpora lutea per ovary, conceptuses per animal or days to ovulation after injection. However, the proportion of females that responded after receiving 0.058 iu eSG g(-1) in the luteal phase was significantly different from that in animals treated with the same dose in the intermediate phase (P < 0.01) and in non-cyclic females treated with 0.058 iu eSG g(-1) (P < 0.02). The main benefits of the treatment were that normal embryos resulted and that 70-78% of non-cyclic animals could be induced to ovulate.

scholarly journals The production of mature oocytes from adult ovaries following primary follicle culture in a marsupial

Reproduction ◽  
2009 ◽  
Vol 138 (2) ◽  
pp. 247-255 ◽  
Author(s):  
A Nation ◽  
L Selwood
Keyword(s):  
Normal Growth ◽  
Primary Follicle ◽  
Follicle Culture ◽  
Nuclear Maturation ◽  
Transmission Electron ◽  
Progressive Growth ◽  
Sminthopsis Macroura ◽  
First Time

A model marsupial culture system has been developed whereby individual primary follicles, obtained from adult ovaries, can be grown in vitro to the antral stage and oocytes retrieved from these follicles can achieve nuclear maturation (metaphase II) in the presence of LH. Primary follicles isolated from adult Sminthopsis macroura ovaries were cultured individually in one of four systems: microdrops under oil, upright, inverted, or roller culture. After 6 days of culture, cumulus–oocyte complexes (COCs) were excised from early antral follicles and incubated for an additional 24 h to assess meiotic competence and the effects of LH and lithium on oocyte maturation. Histology and transmission electron microscopy established normal in vivo standards and verified oocyte and follicular integrity following culture. On day 6 of culture, follicle viability was significantly greater in the inverted system (73%) than in the other three systems (10–46%). The inverted system was the most effective in supporting development with follicles demonstrating progressive growth during culture and showing antral signs by day 4. Meiotic resumption during COC culture was facilitated by LH, but hindered by lithium. The ability to resume meiosis and progress to metaphase II was equivalent in oocytes retrieved following follicle culture and those matured in vivo. This study highlights the importance of oxygen and nutrient availability during marsupial follicle culture, and demonstrates for the first time that primary follicles isolated from adult mammalian ovaries can undergo normal growth and development in vitro, to produce mature, meiotically competent oocytes.

Early pregnancy factor in marsupials

2006 ◽  
Vol 54 (3) ◽  
pp. 211 ◽  
Author(s):  
Y. P. Cruz ◽  
H. Morton ◽  
A. C. Cavanagh ◽  
L. Selwood ◽  
S. D. Wilson ◽  
...  
Keyword(s):  
Early Pregnancy ◽  
Luteal Phase ◽  
Peripheral Circulation ◽  
Monodelphis Domestica ◽  
Laboratory Model ◽  
Physiological Changes ◽  
Early Pregnancy Factor ◽  
Plasma Progesterone ◽  
Sminthopsis Macroura

Maternal recognition of pregnancy in marsupials occurs in more subtle ways than it does in eutherians. For instance, unlike in eutherians, the plasma progesterone profiles of pregnant and non-pregnant animals are similar during the luteal phase. It is typically during the brief luteal phase that both gestation and parturition occur in marsupials. Yet histological and physiological changes have been documented between gravid and non-gravid uteri in certain monovular marsupials and between pregnant and non-pregnant animals in polyovular marsupials. Early pregnancy factor (EPF), a 10.8-kDa serum protein known to be homologous to chaperonin 10, is associated with maternal immunosuppression, embryonic development and pregnancy in eutherian mammals. It has been reported in two Australian marsupials: the dasyurid Sminthopsis macroura and the phalangerid Trichosurus vulpecula. This paper documents its occurrence in the New World didelphid Monodelphis domestica. EPF is detectable by rosette inhibition assay in the peripheral circulation of pregnant but not of non-pregnant or pseudopregnant animals. Our work focuses on the embryo–maternal signalling role of EPF during pregnancy. Because progesterone-driven changes are similar in pregnant and non-pregnant marsupials, these animals are an excellent laboratory model in which to investigate the role of EPF in orchestrating the physiological changes necessary to sustain pregnancy.

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