Females and males often exhibit different survival in nature, and it has been hypothesized that sex chromosomes may play a role in driving differential survival rates. For instance, the Y chromosome in mammals and the W chromosome in birds are often degenerated, with reduced numbers of genes, and loss of the Y chromosome in old men is associated with shorter life expectancy. However, mosaic loss of sex chromosomes has not been investigated in any non-human species. Here, we tested whether mosaic loss of the W chromosome (LOW) occurs with ageing in wild birds as a natural consequence of cellular senescence. Using loci-specific PCR and a target sequencing approach we estimated LOW in both young and adult individuals of two long-lived bird species and showed that the copy number of W chromosomes remains constant across age groups. Our results suggest that LOW is not a consequence of cellular ageing in birds. We concluded that the inheritance of the W chromosome in birds, unlike the Y chromosome in mammals, is more stable.
Metallothionein (MT) is a low molecular weight metal binding protein. It has the unique ability to selective bind trace amounts of toxic heavy metals such as lead and cadmium. It does not bind essential metals such as sodium or calcium. We are developing a novel patented “heavy metal sponge” technology for the removal and recovery of toxic, e.g., lead and mercury, and precious metal, e.g., gold and platinum, from water. MT also has the ability to bind the lanthanides lanthanum and europium. Recombinant MT was cloned into pET vectors with and without a Pel secretory sequence, pPMpel, and pCODAmt, respectively. The protein is expressed in bacteria and purified to near homogeneity from cell lysates by a simple and cost effective method using FPLC anion exchange chromatography. The purity of the preparation was confirmed by SDS‐PAGE. Expression of MT and secretion of the protein using the pPMpel construct is pH dependent. The level of expression from both constructs was the same for IPTG ranging from 0.5 to 2.0 mM. The purified MT was used to determine the potential for removing trace amounts of heavy metal from seawater. The protein was mixed with seawater containing 100 ppt (trillion) of 109Cd. The protein/metal complex was then collected using a membrane filter centrifugal device and the flow through assayed for radioactivity. The efficiency of metal removal was determined from the radioactivity in the flow through. Under these conditions, 88% of the metal was removed from the seawater after a single centrifugation. Grant Funding Source: Funded by a grant from CSUPERB
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