A list of authors and their affiliations appears at the end of the paperWe present a draft genome sequence of the platypus, Ornithorhynchus anatinus. This monotreme exhibits a fascinating combination of reptilian and mammalian characters. For example, platypuses have a coat of fur adapted to an aquatic lifestyle; platypus females lactate, yet lay eggs; and males are equipped with venom similar to that of reptiles. Analysis of the first monotreme genome aligned these features with genetic innovations. We find that reptile and platypus venom proteins have been co-opted independently from the same gene families; milk protein genes are conserved despite platypuses laying eggs; and immune gene family expansions are directly related to platypus biology. Expansions of protein, non-protein-coding RNA and microRNA families, as well as repeat elements, are identified. Sequencing of this genome now provides a valuable resource for deep mammalian comparative analyses, as well as for monotreme biology and conservation.

Lactation, an important characteristic of mammalian reproduction, has evolved by exploiting a diversity of strategies across mammals. Comparative genomics and transcriptomics experiments have now allowed a more in-depth analysis of the molecular evolution of lactation. Milk cell and mammary gland genomic studies have started to reveal conserved milk proteins and other components of the lactation system of monotreme, marsupial, and eutherian lineages. These analyses confirm the ancient origin of the lactation system and provide useful insight into the function of specific milk proteins in the control of lactation. These studies also illuminate the role of milk in the regulation of growth and development of the young beyond simple nutritive aspects.

BackgroundLactation is a key aspect of mammalian evolution for adaptation of various reproductive strategies along different mammalian lineages. Marsupials, such as tammar wallaby, adopted a short gestation and a relatively long lactation cycle, the newborn is immature at birth and significant development occurs postnatally during lactation. Continuous changes of tammar milk composition may contribute to development and immune protection of pouch young. Here, in order to address the putative contribution of newly identified secretory milk miRNA in these processes, high throughput sequencing of miRNAs collected from tammar milk at different time points of lactation was conducted. A comparative analysis was performed to find distribution of miRNA in milk and blood serum of lactating wallaby.ResultsResults showed that high levels of miRNA secreted in milk and allowed the identification of differentially expressed milk miRNAs during the lactation cycle as putative markers of mammary gland activity and functional candidate signals to assist growth and timed development of the young. Comparative analysis of miRNA distribution in milk and blood serum suggests that milk miRNAs are primarily expressed from mammary gland rather than transferred from maternal circulating blood, likely through a new putative exosomal secretory pathway. In contrast, highly expressed milk miRNAs could be detected at significantly higher levels in neonate blood serum in comparison to adult blood, suggesting milk miRNAs may be absorbed through the gut of the young.ConclusionThe function of miRNA in mammary gland development and secretory activity has been proposed, but results from the current study also support a differential role of milk miRNA in regulation of development in the pouch young, revealing a new potential molecular communication between mother and young during mammalian lactation.Electronic supplementary materialThe online version of this article (doi:10.1186/1471-2164-15-1012) contains supplementary material, which is available to authorized users.

No abstract

The gene nmrA of Aspergillus nidulans has been isolated and found to be a homolog of the Neurospora crassa gene nmr-1, involved in nitrogen metabolite repression. Deletion of nmrA results in partial derepression of activities subject to nitrogen repression similar to phenotypes observed for certain mutations in the positively actingareA gene.

The 5' regulatory region of the amdS gene of Aspergillus nidulans, which encodes an acetamidase required for growth on acetamide as a carbon and nitrogen source, contains a CCAAT sequence which is required for setting the basal level of amdS expression. Mobility shift studies have identified a factor in A. nidulans nuclear extracts which binds to this CCAAT sequence. In Saccharomyces cerevisiae the HAP3 gene encodes one component of a multisubunit complex that binds CCAAT sequences. A search of the EMBL and SwissProt databases has revealed an A. nidulans sequence with significant homology to the HAP3 gene adjacent to the previously cloned regulatory gene amdR. Sequencing of the remainder of this region has confirmed the presence of a gene, designated hapC, with extensive homology to HAP3. The predicted amino acid sequence of HapC shows extensive identity to HAP3 in the central conserved domain, but shows little conservation in the flanking sequences. A haploid carrying a hapC deletion has been created and is viable, but grows poorly on all media tested. This null mutant grows especially slowly on acetamide as a sole carbon and nitrogen source, indicating that hapC plays a role in amdS expression. In agreement with this notion, it has been shown that the hapC deletion results in reduced levels of expression of an amdS::lacZ reporter gene and this effect is particularly evident under conditions of carbon limitation. Nuclear extracts prepared from the hapC deletion mutant show no CCAAT binding activity to the amdS or gatA promoters, indicating that hapC may encode a component of the complex binding at this sequence.

SPARC (secreted protein acidic and rich in cysteine)/BM40/Osteonectin is a matricellular protein with multiple effects on cell behaviour. In vitro, its major known functions are anti-adhesive and anti-proliferative, and it is associated with tissue remodelling and cancer in vivo. SPARC is overexpressed in many cancers, including breast cancer, and the effects of SPARC seem to be cell type-specific. To study the effects of SPARC on breast cancer, we transfected SPARC into the MDA-MB-231 BAG, human breast cancer cell line using the Tet-On inducible system. By western analysis, we found low background levels in the MDA-MB-231 BAG and clone X parental cells, and prominent induction of SPARC protein expression after doxycycline treatment in SPARC transfected clones X5, X21, X24 and X75. Induction of SPARC expression did not affect cell morphology or adhesiveness to collagens type I and IV, but it slowed the rate of proliferation in adherent cultures. Cell cycle analysis showed that SPARC slowed the progression to S phase. Doxycycline induction of SPARC also slowed the rate of monolayer wound closure in the cultured wound healing assay. Thymidine inhibition of proliferation abrogated this effect, confirming that it was due to anti-proliferation rather than inhibition of migration. Consistent with this, we were unable to detect any differences in migration and Matrigel outgrowth analysis of doxycycline-stimulated cells. We conclude that SPARC is inhibitory to human breast cancer cell proliferation, and does not stimulate migration, in contrast to its stimulatory effects reported for melanoma (proliferation and migration) and glioma (migration) cells. Similar growth repression by SPARC has been reported for ovarian cancer cells, and this may be a common feature among carcinomas.

Genetic studies have indicated that the facB gene of Aspergillus nidulans is a major regulatory gene involved in acetamide and acetate utilisation. Sequencing of the facB gene revealed that it encodes a protein that contains an N-terminal GAL4-like Zn(II)2Cys6 (or C6 zinc) binuclear cluster for DNA binding, leucine zipper-like heptad repeat motifs and central and C-terminal acidic alpha-helical regions, consistent with a function as a DNA-binding transcriptional activator. The Zn(II)2Cys6 cluster shows strong similarity with those of the Saccharomyces cerevisiae carbon metabolism regulatory proteins CAT8 and SIP4. A significant level of similarity with CAT8 is found throughout the length of the protein, suggesting at least partial functional homology. The facB genes of Aspergillus oryzae and Aspergillus niger were also sequenced and found to be highly conserved. Deletion of the facB gene confirmed that it is required for growth on acetate as a sole carbon source. Functional dissection using deletion and fusion constructs and in vitro mutagenesis indicated that the Zn(II)2Cys6 cluster and the C-terminal end of the protein are required for function.