Three cis-elements required for rice α-amylase Amy3D expression during sugar starvation

Expression of -amylase genes during seedling development plays a key role in production of sugar from the starch stored in the cereal seed. Rice -amylase Amy3D promoter/GUS constructs in transgenic rice cell lines were studied to identify cis elements in the promoter of this metabolite-regulated gene. Three sequences having the greatest effects on Amy3D gene expression included the amylase element (TATCCAT), the CGACG element, and a G box-related element (CTACGTGGCCA). These promoter cis elements are needed for high-level expression of Amy3D under conditions of sugar starvation. The involvement of G box cis-elements in environmental stress responses suggest a link between the nutrient stress and the environmental stress responses of the plant.     

Restoration of semi-natural grasslands,a success for phytophagous beetles (Curculionidae)

Semi-natural pastures have rich plant and animal communities of high conservation value which depend on extensive management. As the area of such land decreases, abandoned semi-natural grasslands have been restored to re-establish biodiversity. Restoration schemes, which include thinning of woody plants and reintroduction of grazing, are mainly designed according to the responses of well-studied groups (such as vascular plants and birds). Weevils (Curculionidae) are a very diverse phytophagous beetle family. Here, we evaluated the restoration success of pastures for weevils (Curculionidae), by comparing their species diversity in abandoned, restored, and continuously grazed semi-natural pastures on 24 sites in central Sweden. Weevils were sampled by sweep-netting. We recorded 3019 weevil individuals belonging to 104 species. There was no statistically significant difference in species numbers between the pasture management treatments. However, weevil species composition of abandoned pastures differed from those in restored and continuously managed pastures, but there was no significant difference in community composition between restored and continuously grazed pastures. The abandoned sites tended to be dominated by polyphagous species, whereas the grazed sites contained more monophagous and oligophagous species. The number of weevil species was positively related to understory vegetation height and connectivity to other semi-natural grasslands and negatively related to the cover of trees and shrubs in the pastures. We conclude that restoration of abandoned semi-natural pastures is a good approach to restore weevil communities. To maintain a species rich weevil community, pastures should be managed to be relatively open, but still have patches of tall field-layer vegetation. Restoration and conservation measures should primarily be targeted on regions and landscapes where a high proportion of semi-natural grassland still remains.     

Site-specific methylation of adenine in the nuclear genome of a eucaryote, Tetrahymena thermophila.

DNA in the polyploid macronucleus of the ciliated protozoan Tetrahymena thermophila contains the modified base N6-methyladenine. We identified two GATC sites which are methylated in most or all of the 45 copies of the macronuclear genome. One site is 2 kilobases 5' to the histone H4-I gene, and the other is 5 kilobases 3' to the 73-kilodalton heat shock protein gene. These sites are de novo methylated between 10 and 16 h after initiation of conjugation, during macronuclear anlage development. The methylation states of these two GATC sites and four other unmethylated GATC sites do not change in the DNA of cells cultured under conditions which change the activity of the genes, including logarithmic growth, starvation, and heat shock.     

Two-dimensional DNA gel electrophoresis as a method for analysis of eukaryotic genome structure: evaluation using Tetrahymena thermophila DNA

There is growing interest in mapping and analyzing complete eukaryotic genomes. Yee and Inouye (in Experimental Manipulation of Gene Expression, pp. 279-290, Academic Press, New York) demonstrated that bacterial chromosomes can be resolved into interpretable patterns of DNA fragments by means of restriction enzyme digestion and electrophoresis in two dimensions. We have begun to explore applications of this procedure to analysis of eukaryotic genomes, which are far more complex. Tetrahymena thermophila was selected as a model organism because its genome is small, roughly equivalent to that of a single human chromosome. In addition, each Tetrahymena cell contains two nuclei which differ in sequence composition and methylation. Our results demonstrate that the Tetrahymena genome can be resolved into complex patterns of fragments in two dimensions. Hybridization to Southern blots of these gels with a multiply repeated sequence probe yielded analyzable patterns of a subset of the genome. The blots reveal alterations in genome structure due to methylation and rearrangement. Future extensions of the method are discussed.     

Superior sagittal sinus thrombosis. Still a killer.

Following treating a case of superior sagittal sinus thrombosis, we did an extensive search of the literature, eliciting 795 cases of the disorder. An analysis showed that even after the introduction of antibiotics, the preponderance of these cases have been diagnosed at autopsy. Our findings raise questions about the current methods of diagnosis and management of superior sagittal sinus thrombosis: Can the correct diagnosis be made earlier? Does a distinction between partial and complete thrombosis call for a different management?