Biomedical subjects

Mark Tucker

Publications and source records attributed to Mark Tucker.

5 recordsLinked to original sources

PubMed2006

Isolation of high-quality RNA from apple (Malus domestica) fruit.

It is difficult to isolate sufficient quantities of high-quality RNA from apple fruit. An abundance of polyphenolic compounds and polysaccharides and a relatively low concentration of RNA in the fruit tissue create conditions that hamper RNA isolation when standard techniques are used. We have developed two RNA isolation methods that include an initial homogenization and extraction with acetone or ethanol. These in turn remove the interfering compounds and precipitate the protein and nucleic acids for subsequent RNA extraction. The quality of RNA was satisfactory with both acetone and ethanol preparations; however, the acetone powder produced consistently higher quantities of RNA.

Acetone↗

PubMed2006

Biofortification of UK food crops with selenium.

Se is an essential element for animals. In man low dietary Se intakes are associated with health disorders including oxidative stress-related conditions, reduced fertility and immune functions and an increased risk of cancers. Although the reference nutrient intakes for adult females and males in the UK are 60 and 75 microg Se/d respectively, dietary Se intakes in the UK have declined from >60 microg Se/d in the 1970s to 35 microg Se/d in the 1990s, with a concomitant decline in human Se status. This decline in Se intake and status has been attributed primarily to the replacement of milling wheat having high levels of grain Se and grown on high-Se soils in North America with UK-sourced wheat having low levels of grain Se and grown on low-Se soils. An immediate solution to low dietary Se intake and status is to enrich UK-grown food crops using Se fertilisers (agronomic biofortification). Such a strategy has been adopted with success in Finland. It may also be possible to enrich food crops in the longer term by selecting or breeding crop varieties with enhanced Se-accumulation characteristics (genetic biofortification). The present paper will review the potential for biofortification of UK food crops with Se.

Crops, Agricultural↗

PubMed2004

Expression analysis of a chicory fructan 1-exohydrolase gene reveals complex regulation by cold.

The gene for a recently identified cDNA, 1-FEH IIa, encoding a fructan 1-exohydrolase was isolated and cloned from Cichorium intybus and a 1149 bp promoter fragment was characterized. An analysis of the genomic 1-FEH IIa sequence indicated that the gene (FEHIIa) consists of six introns and seven exons, which is similar to plant invertase genes. Like invertase genes, FEHIIa also contains the 9 nt mini-exon encoding the tripeptide DPN. A database search for cis-acting response elements within its promoter identified multiple elements that appear to have relevance to cold-induced expression of the gene in field-grown roots. Promoter analysis by transient expression assay demonstrated that the FEHIIa gene promoter is highly expressed in etiolated Cichorium leaves and cold-stored roots, which correlated well with the high level expression detected by RNA blot analysis. Cold also enhanced FEHIIa reporter gene expression in green leaves, however, the reporter gene activity was much lower compared with similar induction experiments in etiolated leaves. Promoter deletion analysis demonstrated the presence of potential cold-responsive ABRE and/or CRT/DRE elements in the -22 to -172 region, while regions -933 to -717 and -493 to -278 contain elements that can down-regulate expression at the conditions used. Characterization of the FEHIIa promoter may provide tools to study cold-induced expression and to increase freezing tolerance in agricultural crops.

Base Sequence↗

PubMed2003

Extraction of high-quality genomic DNA from latex-containing plants.

The isolation of intact, high-molecular-mass genomic DNA is essential for many molecular biology applications including long PCR, endonuclease restriction digestion, Southern blot analysis, and genomic library construction. Many protocols are available for the extraction of DNA from plant material. However, for latex-containing Asteraceae (Cichorioideae) species, standard protocols and commercially available kits do not produce efficient yields of high-quality amplifiable DNA. A cetyltrimethylammonium bromide protocol has been optimized for isolation of genomic DNA from latex-containing plants. Key steps in the modified protocol are the use of etiolated leaf tissue for extraction and an overnight 25 degrees C isopropanol precipitation step. The purified DNA has excellent spectral qualities, is efficiently digested by restriction endonucleases, and is suitable for long-fragment PCR amplification.

Asteraceae↗

PubMed2002

Secure HL7 transactions using Internet mail (Internet draft).

The document describes the applicability of the Internet standardisation efforts on secure electronic data interchange (EDI) transactions for Health Level-7 (HL7), an EDI standard for Healthcare used world-wide. The document heavily relies on the work in progress by the IETF EDIINT working group. It is in most parts a restatement of the EDIINTs requirements document and application statement 1 (AS#1) tailored to the needs of the HL7 audience. The authors tried to make the document as self consistent as possible. The goal is to give to the reader who is not a security or Internet standards expert enough foundational and detail information to enable him to build communication software that complies to the Internet standards. Even though the authors rely on and promote the respective Internet standards and drafts, they did not withstand from commenting on and criticising the work where they see upcoming problems in use with HL7 or other EDI protocols that have not been in the initial focus of the EDIINT working group. The authors make suggestions to add parameters to the specification of the MIME type for EDI messages in RFC 1767 in order to enhance functionality. The authors give use cases for a larger subset of disposition types and modifiers of message disposition notifications. One key issue where the document goes beyond the current EDIINT drafts is the concept of non-repudiation of commitment to an EDI transaction. Secure EDI transactions should be regarded as "distributed contracts," i.e. not only the sending and receiving of single messages should be non-refutable but also the connection between messages interchanges. In anticipation of this requirement HL7 usually requires a response message to be sent to acknowledge every transaction. The authors therefore have the requirement to securely couple an EDI response message to its request message. Given the current shape of RFC 1767 this is generally possible only if a response message is coupled with an MDN receipt and the combination of both signed by the responder. The document describes a protocol to bundle MDN and response that uses the MIME multi-part/related content type in RFC 2112.

Computer Security↗