Two aquaporins,SIP1;1 and PIP1;2, mediate water transport for pollen hydration in the Arabidopsis pistil

Pollination is the crucial initial step that brings together the male and female gametophytes, and occurs at the surface of the stigmatic papilla cell in Arabidopsis thaliana. After pollen recognition, pollen hydration is initiated as a second critical step to activate desiccated mature pollen grains for germination, and thus water transport from pistil to pollen is essential for this process. In this study, we report a novel aquaporin-mediated water transport process in the papilla cell as a control mechanism for pollen hydration. Coupled with a time-series imaging analysis of pollination and a reverse genetic analysis using T-DNA insertion Arabidopsis mutants, we found that two aquaporins, the ER-bound SIP1;1 and the plasma membrane-bound PIP1;2, are key players in water transport from papilla cell to pollen during pollination. In wild type plant, hydration speed reached its maximal value within 5 min after pollination, remained high until 10–15 min. In contrast, sip1;1 and pip1;2 mutants showed no rapid increase of hydration speed, but instead a moderate increase during ∼25 min after pollination. Pollen of sip1;1 and pip1;2 mutants had normal viability without any functional defects for pollination, indicating that decelerated pollen hydration is due to a functional defect on the female side in sip1;1 and pip1;2 mutants. In addition, sip1;1 pip1;2 double knockout mutant showed a similar impairment of pollen hydration to individual single mutants, suggesting that their coordinated regulation is critical for proper water transport, in terms of speed and amount, in the pistil to accomplish successful pollen hydration.     

Stabilizing effect of glutaraldehyde on the respiratory burst NADPH oxidase of guinea pig polymorphonuclear leukocytes

The membrane fraction of guinea pig polymorphonuclear leukocytes stimulated with phorbol myristate acetate exhibits the respiratory burst NADPH oxidase activity. This activity is markedly unstable at 37 degrees C, disappearing with a half-life of 11.0 min. When the membrane fraction was pretreated with 0.1% glutaraldehyde, the NADPH oxidase was found to become more stable; its half-life increased about sixfold without any enhancement of the initial activity. The glutaraldehyde treatment of the membrane fraction also protected the NADPH oxidase against inactivation with 0.1-0.2% Triton X-100. These stabilizing effects of glutaraldehyde on the NADPH oxidase seem to be due to its protein cross-linking ability, since its monovalent analogue, butyraldehyde, did not show any effect on the NADPH oxidase activity. In fact, sodium dodecyl sulfate-polyacrylamide gel electrophoresis revealed that glutaraldehyde cross-linked many proteins constituting the membrane.     

Sister chromatid differential staining by direct staining in Na2HPO4-Giemsa solution and the mechanism involved

The direct staining of BrdU-substituted Chinese hamster chromosomes in a Na₂HPO₄-Giemsa solution without any pretreatments resulted in a B-dark type SCD in which bifilarly substituted (BB) chromatids stained dark and unifilarly substituted (TB) chromatids stained light. Detailed examinations of the staining process suggested that the Na₂HPO₄ solution acts to collapse chromosomes whereas the Giemsa dye works to reconstruct the collapsed chromosomes, and that during the reconstruction process preferential binding of the Giemsa dye to the BB-chromatids occurs to produce the B-dark SCD. It was revealed that not only the time but the temperature at which chromosome preparations are kept prior to use considerably affect the occurrence of SCD.     

Genetic recombination in a chromosomal translocation t(2;8)(p11;q24) of a Burkitt's lymphoma cell line, KOBK101

We analyzed a chromosomal translocation, t(2;8)(p11;q24), in a Burkitt's lymphoma cell line, KOBK101. The translocation reciprocally occurred between a site about 150 bp upstream from the J5 segment in the Ig kappa-encoding gene on chromosome 2 and the A-rich end of an Alu repetitive element located far downstream from the c-myc gene on chromosome 8. Short segments of both parental chromosomes were deleted at the rearrangement site. A sequence related to the heptamer recognition signal for the V-J recombination of Ig genes and a topoisomerase I-recognition sequence were detected at the breakpoints. The V-J recombination occurred on both chromosome 2 and the translocated chromosome 2p- at the J3 and J4 segments, respectively. The J region on the translocated chromosomes was mutated, as compared with that on the untranslocated chromosome, while the Alu element and its upstream sequence were conserved. These results suggest the following aspects to the chromosomal translocation of this cell line. A V-J recombination seems to have occurred at the proximal end of the J4 segment first, and then the translocation took place in the region between the J4 and J5 segments. The translocation may have been mediated by the functions of topoisomerase I and the Alu repetitive sequence located at the breakpoint, although the possibility cannot be ruled out that the recombination machinery for Ig gene rearrangements functioned irregularly.     

Immunomodulating properties of a novel series of protein kinase C activators. The bryostatins

Low concentrations of the protein kinase C activators, bryostatins 1 and 2 synergized with recombinant B cell stimulatory factor-1 in triggering differentiation (granule enzyme expression) and cytotoxic T lymphocyte (CTL) development in naive, resting lymph node T cells. Bryostatin greatly enhances efficiency of recombinant interleukin-2 in triggering development of in vivo primed CTL during in vitro incubation, thereby providing experimental evidence for the efficacious use of lower concentrations of recombinant interleukin-2 for in vivo tumor rejection studies. Both bryostatins 1 and 2 were able to trigger cytotoxicity of CTL clones against antigen-nonbearing target cells and inhibited CTL cytotoxicity against Ag-specific target cells. Bryostatin 1 and 2 synergize with Ca2+ ionophores in triggering the exocytosis of cytolytic granules from CTL at very low concentrations. In view of the lack of tumor promoting activity of the bryostatins, the possible use of these agents in vivo is discussed.     

Approaches to Repigmentation of Vitiligo Skin: New Treatment with Ultrasonic Abrasion,Seed‐Grafting and Psoralen Plus Ultraviolet A Therapy

Vitiligo vulgaris is a common disease throughout the world although its pathogenesis is not yet known. The most frequent treatment used for vitiligo is PUVA (psoralen plus ultraviolet A) and topical steroids but against stable refractory vitiligo, various other surgical techniques have been developed such as autografting, epidermal grafting with suction blisters, epithelial sheet grafting, and transplantation of cultured melanocytes. We have discovered a new method using ultrasonic abrasion, seed‐grafting and PUVA therapy. The ultrasonic surgical aspirator abrades only the epidermis of recipient sites. This easily and safely removes only the epidermis, even on spotty lesions or intricate regions which are difficult to remove using a conventional motor‐driven grinder or liquid nitrogen. Epidermal seed‐grafting can cover more area than sheet‐grafting, and subsequent PUVA treatment can enlarge the area of pigmentation with coalescence of adjacent grafts. In this article, we provide a general overview of the current surgical therapies including our method for treating stable refractory vitiligo.     

The cDNA Sequence of NS3-Glycoprotein from Brassica campestris and its Homology to Related Proteins

A cDNA clone encoding NS₃-glycoprotein was isolated from stigmasof Brassica campestris. NS-glycoproteins correspond to the SLRI-glycoproteinsof B. oleracea and are highly conserved within the species.These data suggest that the NS-glycoproteins may play a rolein discrimination between species in the fertilization systemof Brassica. (Received September 4, 1992; Accepted November 9, 1992)