Pollination of the Lady's slipper orchid (Cypripedium calceolus) in Scandinavia – taxonomic and conservational aspects

The Lady's slipper orchid Cypripedium calceolus L. is considered one of the most beautiful orchids of Europe. Consequently, the species has suffered from over-collecting and is now critically endangered in many countries. Although pollination success is suspected to influence the long-term survival of Cypripedium calceolus , relatively little is known about the identity of its pollinators in mainland Sweden – a region that comprises the largest European populations. In order to identify which species pollinate eight representative populations in mainland Sweden, we observed and sampled visitors to flowers using a standardized protocol. Specimens were identified and any pollen smear found on their body was examined for the presence of Cypripedium pollen. Nine species were recognized as effective pollen vectors ( Andrena cineraria, A. carantonica, A. haemorrohoa, A. helvola, A. nigroaenea, A. praecox, Colletes cunicularius, Lasioglossum fratellum and L. fulvicorne ), four of them for the first time in Scandinavia. This is the first time that a species of Colletes is reported to carry pollen of Cypripedium in this region. All but one specimens were females. Our results suggest a taxonomically heterogeneous pollinator fauna for Cypripedium calceolus and are discussed in light of the management of this species.     

Electrophoretic transfer of DNA, RNA and protein onto diazobenzyloxymethyl (DBM) - paper.

A method has been developed for the electrophoretic transfer of DNA, RNA, protein and ribonucleoprotein particles from a variety of gels onto diazobenzyloxymethyl (DBM) - paper. Conditions for the electrophoretic transfer of these macromolecules have been optimized to allow for nearly quantitative transfer and covalent coupling. DNA and RNA electrophoretically transferred to DBM-paper retain their ability to hybridize with specific probes. The high efficiency of transfer and the high capacity of DBM-paper for nucleic acids makes possible the sensitive detection of specific nucleotide sequences. Similar efficiency is achieved in electrophoretic transfer and covalent coupling of proteins to DBM-paper. Macromolecules can also be electrophoretically transferred and bound to DBM-paper incapable of covalent bond formation. Their elution from the paper in high salt provides a new and useful preparative method for isolation of DNA, RNA and protein.     

U1 small nuclear RNA genes are located on human chromosome 1 and are expressed in mouse-human hybrid cells.

The majority, and perhaps all, of the genes for human U1 small nuclear RNA (U1 RNA) were shown to be located on the short arm of human chromosome 1. These genes were mapped by Southern blot analysis of DNA from rodent-human somatic cell hybrids, using the 5' region of a human U1 RNA gene as a human-specific probe. This probe hybridized to DNA fragments present only in digests of total human DNA or to the DNAs of cell lines which contained human chromosome 1. The major families of human U1 RNA genes were identified, but some human genes may have gone undetected. Also, the presence of a few U1 RNA genes on human chromosome 19 could not be ruled out. In spite of the lack of extensive 5'-flanking-region homology between the human and mouse U1 RNA genes, the genes of both species were efficiently transcribed in the hybrid cells, and the U1 RNAs of both species were incorporated into specific ribonucleoprotein particles.     

Isolation and characterization of genomic mouse DNA clones containing sequences homologous to tRNAs and 5S rRNA.

We have cloned and characterized three fragments of Balb/c mouse DNA which hybridize to mouse cell tRNAs. Fractionation of the tRNAs which hybridize to these clones reveals that two of the clones, lambda Mt-4A and lambda Mt-6A hybridize to only one or two tRNAs, while one clone, lambda Mt-4B, hybridizes to at least seven tRNAs. Two of the tRNAs were identified as tRNAProCCG and tRNAGlyGGA, and others have been identified as tRNAs which are selectively encapsidated into virions of murine leukemia virus and avian reticuloendotheliosis virus. The DNA sequences of putative genes for tRNAProCCG and tRNAGlyGGA, plus flanking regions, were determined. A clone of Balb/c mouse DNA which selectively hybridized to 5S rRNA was also isolated and partially characterized.     

A spinal organ of proprioception for integrated motor action feedback

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SV40 T-antigen-binding sites within the 5'-flanking regions of human U1 and U2 genes.

The 5' flanking regions of the genes (U1 and U2) encoding the human U1 and U2 small nuclear RNAs (snRNAs) each contain sequences that bind specifically to the simian virus (SV40) large tumor antigen (T.Ag). Substitution of these sites with sequences that lack T.Ag-binding sites did not block accumulation of U1 or U2 snRNA in a variety of cell types, but deletion of these regions resulted in the total loss of expression. Thus, these sequences may serve only a spacing function, and the T.Ag-binding sites appear not to be necessary for expression. However, coexpression of T.Ag markedly reduced expression of a U1 gene containing a high-affinity T.Ag-binding site (from the SV40 genome) in place of the U1 T.Ag-binding site. In contrast, coexpression of T.Ag enhanced synthesis of U2, but not U1, snRNA, independent of the presence of the T.Ag-binding sites. Thus, while the consensus T.Ag-binding sites within the U1 and U2 promoter regions do not appear to influence expression, the binding of SV40 T.Ag to a high-affinity site can lead to significant repression of a strong snRNA promoter, and T.Ag can enhance expression of another in the absence of a known binding site.