Identification of the mRNA encoding interleukin-6 and its receptor, interleukin-6 receptor α, in five marsupial species

Red-tailed phascogales: A review of their biology and importance as model marsupial species

There are many limitations when using traditional laboratory species. Limits on variation, may result in limited outcomes, at both the species and individual level, due to different individuals/species having diverse physiological processes, or differing molecular and genetic mechanisms. By using a variety of model species, we will be able to develop creative solutions to biological problems and identify differences of which we were not previously aware. The laboratory mouse has been a suitable model species for various mammalian studies, however most are bred specifically for laboratory research with limited variability due to selective breeding. Marsupial models offer unique research opportunities compared to eutherian models. We believe that there should be an expansion in marsupial model species, and the introduction of the red-tailed phascogale (Phascogale calura), a dasyurid marsupial, should be one of them. Phascogales are easily managed in captivity, and there are now multiple studies involving their development, reproduction, nutrition, behavior and immune system, which can serve as a baseline for future studies. The addition of the phascogale as a model species will improve future mammalian studies by introducing variability and offer alternate solutions to biological problems, particularly in the areas of genetics, nutrition, immunology, the neuro-endocrine system, and ageing, due to their semelparous reproductive strategy and hence, subsequent predictive physiology. In this review, we provide information based on existing research on red-tailed phascogales to support their inclusion as a model species.

A New IL6 Isoform in Chinese Soft-Shelled Turtle (Pelodiscus sinesis) Discovered: Its Regulation during Cold Stress and Infection

The Chinese soft-shelled turtle (Pelodiscus sinesis) is a widely cultured commercial species in East and Southeast Asian countries. The turtles frequently suffer from acute cold stress during farming in China. Stress-induced factor such as Interleukin-6 (IL6) is a multifunctional molecule that plays important roles in innate and adaptive immune response. In the present study, we found that the turtle possessed two IL6 transcripts, where one IL6 transcript contained a signal peptide sequence (psIL6), while the other IL6 transcript (psIL6ns) possessed no such signal peptide gene. To test any differential expression of the two isoforms during temperature and microbial stress, turtles were adapted to optimal environmental water temperature (25 °C), stressed by acute cooling for 24 h, followed with the challenge of Aeromonas hydrophila (1.8 × 10⁸ CFU) or Staphylococcus aureus (5.8 × 10⁸ CFU). Gene characterization revealed that psIL6ns, a splicer without codons encoding a signal peptide and identical to the one predicted from genomic sequence, and psIL6, a splicer with codons encoding a signal peptide, were both present. Inducible expression was documented in primary spleen cells stimulated with ConA and poly I: C. The splenic and intestinal expression of psIL6ns and psIL6 was increased in response to temperature stress and bacterial infection.

Limitations in the isolation and stimulation of splenic mononuclear cells in a dasyurid marsupial, Phascogale calura

OBJECTIVE

Marsupials suffer from an increasing number of stressors in this changing world. Functional studies are thus needed to broaden our understanding of the marsupial immune system. The red-tailed phascogale (Phascogale calura) is a small Australian marsupial previously used in descriptive immunological studies. Here, we aimed to develop functional assays by isolating and stimulating blood and spleen mononuclear cells in vitro.

RESULTS

While peripheral blood mononuclear cell (PBMC) were relatively easy to isolate, only 105 mononuclear cells (> 90% purity and > 75% viability) could be recovered from the spleen, independently of the sex and age of the animal or the centrifugation time and speed tested. The pores of the mesh sieve used for tissue homogenization might have been too big to yield a single cell suspension. Nevertheless, in spite of the overall low number of cells recovered, PBMC and splenic mononuclear cells were successfully activated in preliminary trials with phytohemaglutinin. This activation state was evidenced by a change in shape and the presence of small cell aggregations in the mitogen-stimulated cultures. A non-radioactive colorimetric assay was also performed to confirm cell proliferation in these wells. This work highlights the importance of developing and reporting detailed methodological protocols in non-traditional research species.

Transcriptomic changes in the pre-implantation uterus highlight histotrophic nutrition of the developing marsupial embryo

Early pregnancy is a critical time for successful reproduction; up to half of human pregnancies fail before the development of the definitive chorioallantoic placenta. Unlike the situation in eutherian mammals, marsupial pregnancy is characterised by a long pre-implantation period prior to the development of the short-lived placenta, making them ideal models for study of the uterine environment promoting embryonic survival pre-implantation. Here we present a transcriptomic study of pre-implantation marsupial pregnancy, and identify differentially expressed genes in the Sminthopsis crassicaudata uterus involved in metabolism and biosynthesis, transport, immunity, tissue remodelling, and uterine receptivity. Interestingly, almost one quarter of the top 50 genes that are differentially upregulated in early pregnancy are putatively involved in histotrophy, highlighting the importance of nutrient transport to the conceptus prior to the development of the placenta. This work furthers our understanding of the mechanisms underlying survival of pre-implantation embryos in the earliest live bearing ancestors of mammals.