Hybrid plants preserve unique genetic variation in the St Helena endemic trees <Emphasis Type="Italic">Commidendrum rotundifolium</Emphasis> DC Roxb. and <Emphasis Type="Italic">C. spurium</Emphasis> (G.Forst.) DC

The island of St Helena in the South Atlantic Ocean has a rich endemic flora, with 10 endemic genera and 45 recognised endemic species. However, populations of most endemic species have undergone dramatic reductions or extinction due to over-exploitation, habitat destruction and competition from invasive species. Consequently, endemic species are likely to have lost genetic variation, in some cases to extreme degrees. Here, the entire extant wild populations and all planted trees in seed orchards, of two critically endangered species in the endemic genus Commidendrum (Asteraceae), C. rotundifolium and C. spurium, were sampled to assess levels of genetic variation and inbreeding. Six new microsatellite loci were developed from next-generation sequence data, and a total of 190 samples were genotyped. Some seed orchard trees contained alleles from both wild C. rotundifolium and C. spurium indicating they could be hybrids and that some backcrossing may have occurred. Some of these trees were more similar to C. rotundifolium than C. spurium both genetically and morphologically. Importantly, allelic variation was detected in the putative hybrids that was not present in wild material. C. rotundifolium is represented by just two individuals one wild and one planted and C. spurium by seven, therefore the seed orchard trees comprise an important part of the total remaining genetic diversity in the genus Commidendrum.     

Sulfated fucans from the egg jellies of the closely related sea urchins Strongylocentrotus droebachiensis and Strongylocentrotus pallidus ensure species-specific fertilization.

Sulfated polysaccharides from egg jelly are the molecules responsible for inducing the sperm acrosome reaction in sea urchins. This is an obligatory event for sperm binding to, and fusion with, the egg. The sulfated polysaccharides from sea urchins have simple, well defined repeating structures, and each species represents a particular pattern of sulfate substitution. Here, we examined the egg jellies of the sea urchin sibling species Strongylocentrotus droebachiensis and Strongylocentrotus pallidus. Surprisingly, females of S. droebachiensis possess eggs containing one of two possible sulfated fucans, which differ in the extent of their 2-O-sulfation. Sulfated fucan I is mostly composed of a regular sequence of four residues ([4-alpha-l-Fucp-2(OSO3)-1-->4-alpha-l-Fucp-2(OSO3)-1-->4-alpha-l-Fucp-1-->4-alpha-l-Fucp-1]n), whereas sulfated fucan II is a homopolymer of 4-alpha-l-Fucp-2(OSO3)-1 units. Females of S. pallidus contain a single sulfated fucan with the following repeating structure: [3-alpha-l-Fucp-2(OSO3)-1-->3-alpha-l-Fucp-2(OSO3)-1-->3-alpha-l-Fucp-4(OSO3)-1-->3-alpha-l-Fucp-4(OSO3)-1]n. The egg jellies of these two species of sea urchins induce the acrosome reaction in homologous (but not heterologous) sperm. Therefore, the fine structure of the sulfated alpha-fucans from the egg jellies of S. pallidus and S. droebachiensis, which differ in their sulfation patterns and in the position of their glycosidic linkages, ensures species specificity of the sperm acrosome reaction and prevents interspecies crosses. In addition, our observations allow a clear appreciation of the common structural features among the sulfated polysaccharides from sea urchin egg jelly and help to identify structures that confer finer species specificity of recognition in the acrosome reaction.     

Parental Investment Strategies Determined by Expected Benefits

The purpose of this study was to determine whether parental investment decisions are made on the basis of cumulative past investment or the prospects of expected benefits minus costs. Through clutch size manipulations at nests of Redwinged Blackbirds, Agelaius phaeniceus, we obtained ♂♂ with equal past investment but varying expected benefits. Parental investment was measured by intensity of nest defense against a dummy predator at the nest. Results indicate expected benefits minus costs, rather than cumulative investment, determine parental investment decisions.     

Reduced capacitative calcium entry correlates with vesicle accumulation and apoptosis

A preneoplastic variant of Syrian hamster embryo cells, sup(+), exhibits decreased endoplasmic reticulum calcium levels and subsequently undergoes apoptosis in low serum conditions (Preston, G. A., Barrett, J. C., Biermann, J. A., and Murphy, E. (1997) Cancer Res. 57, 537-542). This decrease in endoplasmic reticulum calcium appears to be due, at least in part, to reduced capacitative calcium entry at the plasma membrane. Thus we investigated whether inhibition of capacitative calcium entry per se could reduce endoplasmic reticulum calcium and induce apoptosis of cells. We find that treatment with either SKF96365 (30-100 microM) or cell-impermeant 1,2-bis(o-amino-5-bromophenoxy)ethane-N,N,N', N'-tetraacetic acid (5-10 mM) is able to induce apoptosis of cells in conditions where apoptosis does not normally occur. Because previous work has implicated vesicular trafficking as a mechanism of regulating capacitative calcium entry, we investigated whether disruption of vesicular trafficking could lead to decreased capacitative calcium entry and subsequent apoptosis of cells. Coincident with low serum-induced apoptosis, we observed an accumulation of vesicles within the cell, suggesting deregulated vesicle trafficking. Treatment of cells with bafilomycin (30-100 nM), an inhibitor of the endosomal proton ATPase, produced an accumulation of vesicles, decreased capacitative entry, and induced apoptosis. These data suggest that deregulation of vesicular transport results in reduced capacitative calcium entry which in turn results in apoptosis.     

Identification and functional characterization of a new member of the human Mcm protein family: hMcm8

The six minichromosome maintenance proteins (Mcm2–7) are required for both the initiation and elongation of chromosomal DNA, ensuring that DNA replication takes place once, and only once, during the S phase. Here we report on the cloning of a new human Mcm gene (hMcm8) and on characterisation of its protein product. The hMcm8 gene contains the central Mcm domain conserved in the Mcm2–7 gene family, and is expressed in a range of cell lines and human tissues. hMcm8 mRNA accumulates during G₁/S phase, while hMcm8 protein is detectable throughout the cell cycle. Immunoprecipitation-based studies did not reveal any participation of hMcm8 in the Mcm3/5 and Mcm2/4/6/7 subcomplexes. hMcm8 localises to the nucleus, although it is devoid of a nuclear localisation signal, suggesting that it binds to a nuclear protein. In the nucleus, the hMcm8 structure-bound fraction is detectable in S, but not in G₂/M, phase, as for hMcm3. However, unlike hMcm3, the hMcm8 structure-bound fraction is not detectable in G₁ phase. Overall, our data identify a new Mcm protein, which does not form part of the Mcm2–7 complex and which is only structure-bound during S phase, thus suggesting its specific role in DNA replication.     

Influence of lunar phases on suicide: the end of a myth? A population-based study

The hypothesis of lunar influence on suicide remains widespread, despite the fact that little scientific evidence to substantiate it. We conducted a population-based study to assess the influence of the lunar phases on suicides according to age, sex, and chosen method. The study included all suicides in Middle Franconia between 1998 and 2003. From a population-based sample of 3351 events, the files of 3054 suicides (1949 males and 1105 females) were complete for the study variables. Data were categorized by lunar phase, sex, age, and chosen method—“violent” vs. “non-violent” acts. No significant relationship was detected between the full, absent, and moon's interphases and suicide incidence. Nevertheless, there was a weak association between the absent moon and choice of a non-violent suicide method in men aged less than the median of 40.2 yrs. There was no evidence of a relationship between suicide and lunar phase. Some explanations for this phenomenon are discussed.