T(11;18)(q21;q21)-positive gastrointestinal MALT lymphomas are heterogeneous with respect to the V_H gene mutation status

AIM: To investigate how t(11;18)(q21;q21)-positive gastrointestinal MALT lymphomas relate to other marginal zone lymphomas with respect to the somatic mutation pattern of the VH genes and the expression of the marker CD27. METHODS: The VH gene of 7 t(11;18)(q21;q21)-positive gastrointestinal MALT lymphomas was amplif iedby PCR using family specif ic VH primers and a consensus JH primer. PCR products were sequenced and mutation analysis of the CDR and the FR regions was performed. All cases were immunostained for CD27. RESULTS: One case showed unmutated VH genes while the others showed mutated VH genes with mutation frequencies ranging from 1.3 to 14.7% and with evidence of antigen selection in 2 cases. These data suggest that the translocation t(11;18)(q21;q21) can target either B-cells at different stages of differentiation or naive B-cells that retain the capacity to differentiate upon antigen stimulation. All cases but one displayed weak to strong CD27 expression which did not correlate with the VH gene mutation status. CONCLUSION: t(11;18)(q21;q21)-positive gastro- intestinal MALT lymphomas are heterogeneous with respect to the VH mutation status and CD27 is not a marker of somatically mutated B-cells.

A Transgenic Study on Affecting Potato Tuber Yield by Expressing the Rice Sucrose Transporter Genes OsSUT5Z and OsSUT2M

In many plants, sucrose transporters are essential for both sucrose exports from sources and imports into sinks, indicating a function in assimilate partitioning. To investigate whether sucrose transporters can improve the yield of starch plant, potato plants （Solanum tuberosum L. cv. D^siree） were transformed with cDNAs of the rice sucrose transporter genes OsSUT5Z and OsSUT2M under the control of a tuber- specific, class-I patatin promoter. Compared to the controls, the average fructose content of OsSUTSZ transgenic tubers significantly increased. However, the content of the sugars and starch in the OsSUT2M transgenic potato tubers showed no obvious difference. Correspondingly, the average tuber yield, average number of tubers per plant and average weight of single tuber showed no significant difference in OsSUT2M transgenic tubers with controls. In the OsSUTSZ transgenic lines, the average tuber yield per plant was 1.9-fold higher than the controls, and the average number of tubers per plant increased by more than 10 tubers on average, whereas the average weight of a single tuber did not increase significantly. These results suggested that the average number of tubers per plant showed more contribution than the average weight of a single tuber to the tuber yield per plant.

Phosphorylation‐dependent Traffcking of Plasma Membrane Proteins in Animal and Plant Cells

In both unicellular and multicellular organisms, transmembrane （TM） proteins are sorted to and retained at specific membrane domains by endomembrane trafficking mechanisms that recognize sorting signals in the these proteins. The trafficking and distribution of plasma membrane （PM）-localized TM proteins （PM proteins）, especially of those PM proteins that show an asymmetric distribution over the PM, has received much attention, as their proper PM localization is crucial for elementary signaling and transport processes, and defects in their localization often lead to severe disease symptoms or developmental defects. The subcellular localization of PM proteins is dynamically regulated by post-translational modifications, such as phosphorylation and ubiquitination. These modificaitons mostly occur on sorting signals that are located in the larger cytosolic domains of the cargo proteins. Here we review the effects of phosphorylation of PM proteins on their trafficking, and present the key examples from the animal field that have been subject to studies for already several decades, such as that of aquaporin 2 and the epidermal growth factor receptor. Our knowledge on cargo trafficking in plants is largely based on studies of the family of PIN FORMED （PIN） carriers that mediate the efflux of the plant hormone auxin. We will review what is known on the subcellular distribution and trafficking of PIN proteins, with a focus on how this is modulated by phosphorylation, and identify and discuss analogies and differences in trafficking with the well-studied animal examples.

Cell Polarity and Development

All ceiis show some degree of poiarity, either by asymmetrically distributed membrane or cytosolic components. Even in bacterial cells that do not have the eukaryotic membrane compartmentalization of the cytoplasm, proteins can be localized at specific areas. In rod-shaped bacteria, many processes such as signaling, flagella formation, and DNA uptake occur at the cell poles. In addition,

An INDEHISCENT-Controlled Auxin Response Specifies the Separation Layer in Early Arabidopsis Fruit

Seed dispersal is an important moment in the life cycle of a plant species. In Arabidopsis thaliana, it is dependent on transcription factor INDEHISCENT （IND）-mediated specification of a separation layer in the dehiscence zone found in the margin between the valves （carpel walls） and the central replum of the developing fruit. It was proposed that IND specifies the separation layer by inducing a local auxin minimum at late stages of fruit development. Here we show that morphological differences between the ind mutant and wild-type fruit already arise at early stages of fruit development, coinciding with strong IND expression in the valve margin. We show that IND-reduced PIN-FORMED3 （PIN3） auxin efflux carrier abundance leads to an increased auxin response in the valve margin during early fruit develop- ment, and that the concomitant cell divisions that form the dehiscence zone are lacking in ind mutant fruit. Moreover, IND promoter-driven ectopic expression of the AGC kinases PINOID （PID） and WAG2 induced indehiscence by expelling auxin from the valve margin at stages 14-16 of fruit development through increased PIN3 abundance. Our results show that IND, besides its role at late stages of Arabi- dopsis fruit development, functions at early stages to facilitate the auxin-triggered cell divisions that form the dehiscence zone.