Expression of PGK-A in the Australian brush-tailed possum,Trichosurus vulpecula (Kerr), consistent with paternal X inactivation

An extensive survey of erythrocytes of marsupials other than kangaroos for electrophoretic variation in X-linked enzymes revealed two rare PGK-A phenotypes in the phalangerid Trichosurus vulpecula and one in Trichosurus caninus. Four putatively heterozygous females expressed only the variant allelic isozyme in some tissues but expressed a trace of the normal isozyme in others. A putatively hemizygous male expressed only the variant isozyme in all tissues. The phenotypic patterns were consistent with those observed in kangaroos known to exhibit partial or complete paternal X inactivation in cells of females. Two of the T. vulpecula were a mother and her female pouch young, further suggesting that paternal X inactivation occurs in T. vulpecula. This peculiar mechanism of dosage compensation may not be restricted to kangaroos.This work was supported by grants to D. W. C. from the Australian Research Grants Committee and Macquarie University, J. L. V. was the recipient of a Fulbright-Hays Award from the Australian-American Educational Foundation and a postgraduate fellowship from General Motors-Holden.     

Retrospective study of morbidity and mortality of captive jaguars (Panthera onca) in North America: 1982–2002

One hundred seventy‐two medical records of captive jaguars (Panthera onca) were examined from 30 American Zoo and Aquarium Association (AZA) institutions housing jaguars between 1982–2002. The study determined common causes of morbidity and mortality, and the influence of age, gender, and melengestrol‐acetate (MGA) exposure on these rates. The most common causes of morbidity in captive jaguars were found to be dental, gastrointestinal, integumentary, and musculoskeletal diseases. Prevalence of types of disease varied with age, with older animals experiencing a higher prevalence of multiple types of disease. Females developed reproductive disease more frequently than males, and the data suggest that MGA exposure increased the risk of developing female reproductive disease. The most common causes of mortality were reproductive diseases in females and musculoskeletal diseases in males. There was a high rate of neonate and pediatric mortality, primarily due to stillbirths or unexplained neonatal death, trauma, and pneumonia. Other diseases or clinical signs that seemed remarkable were a high prevalence of episodes of epistaxis among young, as well as old, jaguars. Based on these findings, management suggestions for the captive jaguar population are presented. Zoo Biol 0:1–12, 2006. © 2006 Wiley‐Liss, Inc.     

Complexity of developmental control: analysis of embryonic cell lineage specification in Caenorhabditis elegans using pes-1 as an early marker.

In the early Caenorhabditis elegans embryo five somatic founder cells are born during the first cleavages. The first of these founder cells, named AB, gives rise to 389 of the 558 nuclei present in the hatching larva. Very few genes directly involved in the specification of the AB lineage have been identified so far. Here we describe a screen of a large collection of maternal-effect embryonic lethal mutations for their effect on the early expression of a pes-1::lacZ fusion gene. This fusion gene is expressed in a characteristic pattern in 14 of the 32 AB descendants present shortly after the initiation of gastrulation. Of the 37 mutations in 36 genes suspected to be required specifically during development, 12 alter the expression of the pes-1::lacZ marker construct. The gene expression pattern alterations are of four types: reduction of expression, variable expression, ectopic expression in addition to the normal pattern, and reduction of the normal pattern together with ectopic expression. We estimate that approximately 100 maternal functions are required to establish the pes-1 expression pattern in the early embryo.     

Structure, sequence and function of a marsupial LIF gene: conservation of IL-6 family cytokines.

Leukaemia Inhibitory Factor (LIF) is a multifunctional cytokine with an obligate role in the mouse in embryonic implantation. In this paper we demonstrate the existence of a functional LIF gene in the marsupial Sminthopsis crassicaudata, and the presence of LIF-related sequences in the monotreme Tachyglossus aculeatus (Australian echidna). Isolation of genomic and cDNA clones from S. crassicaudata, indicated that the LIF gene is highly conserved between marsupials and monotremes in terms of sequence and genomic organisation. Critical functional residues within the LIF sequence were also conserved including residues implicated in intracellular LIF activity, and in interaction with the receptor subunits LIFR and gp130. These findings suggest that the structure and biochemical function of the protein is likely to be conserved. Consistent with this, purified recombinant S. crassicaudata LIF interacted functionally with mouse receptor components and was sufficient for maintenance of mouse embryonic stem (ES) cells in the undifferentiated state. Conservation of LIF outside eutherians is intriguing given the markedly divergent reproductive strategies which include, for some marsupial species, embryonic diapause, and in monotremes, the absence of implantation. The availability of marsupial LIF probes provides an opportunity to investigate conservation of expression and function in these mammals.     

FERTILE CONIFEROPHYTE REMAINS FROM THE LATE TRIASSIC DEEP RIVER BASIN,NORTH CAROLINA

Seed cones (Compsostrobus neotericus gen. et sp. nov.), pollen cones, and vegetative remains of coniferophytes occur in Upper Triassic rocks of the Deep River Basin (Pekin Formation) of Central North Carolina. Seed cones have spatulate ovuliferous scales, each with two ovules and subtended by an elongated bract with an attenuate tip. Cuticle of seed cones resembles that of leaves on vegetative axes. Slender leaves are borne along two sides of the axis. Pollen cones have helically arranged microsporophylls, each with two abaxial sporangia bearing pollen grains of the Alisporites type. Seed cones, pollen cones, and vegetative remains suggest a coniferophyte very modern in aspect.