Synergistic interaction of three ERECTA-family receptor-like kinases controls Arabidopsis organ growth and flower development by promoting cell proliferation

Growth of plant organs relies on coordinated cell proliferation followed by cell growth, but the nature of the cell-cell signal that specifies organ size remains elusive. The Arabidopsis receptor-like kinase (RLK) ERECTA regulates inflorescence architecture. Our previous study using a dominant-negative fragment of ERECTA revealed the presence of redundancy in the ERECTA-mediated signal transduction pathway. Here, we report that Arabidopsis ERL1 and ERL2, two functional paralogs of ERECTA, play redundant but unique roles in a part of the ERECTA signaling pathway, and that synergistic interaction of three ERECTA-family RLKs define aerial organ size. Although erl1 and erl2 mutations conferred no detectable phenotype, they enhanced erecta defects in a unique manner. Overlapping but distinct roles of ERL1 and ERL2 can be ascribed largely to their intricate expression patterns rather than their functions as receptor kinases. Loss of the entire ERECTA family genes led to striking dwarfism, reduced lateral organ size and abnormal flower development, including defects in petal polar expansion, carpel elongation, and anther and ovule differentiation. These defects are due to severely reduced cell proliferation. Our findings place ERECTA-family RLKs as redundant receptors that link cell proliferation to organ growth and patterning.     

The composition of newly synthesized proteins in the endoplasmic reticulum determines the transport pathways of soybean seed storage proteins

Glycinin (11S) and beta-conglycinin (7S) are major storage proteins in soybean (Glycine max L.) seeds and accumulate in the protein storage vacuole (PSV). These proteins are synthesized in the endoplasmic reticulum (ER) and transported to the PSV by vesicles. Electron microscopic analysis of developing soybean cotyledons of the wild type and mutants with storage protein composition different from that of the wild type showed that there are two transport pathways: one is via the Golgi and the other bypasses it. Golgi-derived vesicles were observed in all lines used in this study and formed smooth dense bodies with a diameter of 0.5 to several micrometers. ER-derived protein bodies (PBs) with a diameter of 0.3-0.5 microm were observed at high frequency in the mutants containing higher amount of 11S group I subunit than the wild type, whereas they were hardly observed in the mutants lacking 11S group I subunit. These indicate that pro11S group I may affect the formation of PBs. Thus, the composition of newly synthesized proteins in the ER is important in the selection of the transport pathways.     

Arterial anatomical features of the upper palpebra

The arterial anatomical features of the upper palpebra were examined in both sides of seven fresh cadavers that had been systemically injected with a lead oxide/gelatin mixture. All specimens were stereoscopically radiographed for analysis of the three-dimensional structure of the arteries and were macroscopically dissected for observation of the relationships between the arteries and the other tissues. Cross-sections were prepared from one specimen and examined histologically. In all cases, there were four arterial arcades in the upper palpebra, namely, the marginal, peripheral, superficial orbital, and deep orbital arcades. Each arcade provided small vertical branches. The vertical branches coursed on both sides of the orbicularis oculi muscle and on both sides of the tarsal plate. From these small vertical branches, fine vessels branched off to the skin, muscle, and tarsal plate. These findings are important for avoiding complications such as bleeding and are useful for designing local flaps, such as switch flaps, for reconstructive surgical procedures.     

Vascular anatomy of the anterolateral thigh flap

Arterial and venous anatomy and their relation to the anterolateral thigh flap were examined in 10 specimens of six fresh cadavers in which radiopaque materials were injected into both the arterial and venous systems. Territories and positions of individual perforating arteries were measured, and the venous drainage pathway of the flap was analyzed. All specimens were radiographed stereoscopically to observe the three-dimensional structure of the arteries and veins. The territory of each perforating artery was smaller than expected. Most of the venous blood that had perfused the dermis was considered to pool in a polygonal venous network located in the skin layer and to enter the descending branch of the lateral circumflex femoral artery through large descending veins. The venous territories were considered different from the arterial territories. The findings in this study suggest that the design of the anterolateral thigh flap should be based on the venous architecture rather than on the arterial architecture and that the flap survival rate might be improved if thinning is performed appropriately.     

Salt-inducible multidrug efflux pump protein in the moderately halophilic bacterium Chromohalobacter sp

It has been known that halophilic bacteria often show natural resistance to antibiotics, dyes, and toxic metal ions, but the mechanism and regulation of this resistance have remained unexplained. We have addressed this question by identifying the gene responsible for multidrug resistance. A spontaneous ofloxacin-resistant mutant derived from the moderately halophilic bacterium Chromohalobacter sp. strain 160 showed a two- to fourfold increased resistance to structurally diverse compounds, such as tetracycline, cefsulodin, chloramphenicol, and ethidium bromide (EtBr), and tolerance to organic solvents, e.g., hexane and heptane. The mutant produced an elevated level of the 58-kDa outer membrane protein. This mutant (160R) accumulated about one-third the level of EtBr that the parent cells did. An uncoupler, carbonyl cyanide m-chlorophenylhydrazone, caused a severalfold increase in the intracellular accumulation of EtBr, with the wild-type and mutant cells accumulating nearly equal amounts. The hrdC gene encoding the 58-kDa outer membrane protein has been cloned. Disruption of this gene rendered the cells hypersusceptible to antibiotics and EtBr and led to a high level of accumulation of intracellular EtBr. The primary structure of HrdC has a weak similarity to that of Escherichia coli TolC. Interestingly, both drug resistance and the expression of HrdC were markedly increased in the presence of a high salt concentration in the growth medium, but this was not observed in hrdC-disrupted cells. These results indicate that HrdC is the outer membrane component of the putative efflux pump assembly and that it plays a major role in the observed induction of drug resistance by salt in this bacterium.     

Role of primary sensorimotor cortex and supplementary motor area in volitional swallowing: a movement-related cortical potential study

We investigated the role of the cerebral cortex, particularly the face/tongue area of the primary sensorimotor (SMI) cortex (face/tongue) and supplementary motor area (SMA), in volitional swallowing by recording movement-related cortical potentials (MRCPs). MRCPs with swallowing and tongue protrusion were recorded from scalp electrodes in eight normal right-handed subjects and from implanted subdural electrodes in six epilepsy patients. The experiment by scalp EEG in normal subjects revealed that premovement Bereitschaftspotentials (BP) activity for swallowing was largest at the vertex and lateralized to either hemisphere in the central area. The experiment by epicortical EEG in patients confirmed that face/tongue SMI and SMA were commonly involved in swallowing and tongue protrusion with overlapping distribution and interindividual variability. BP amplitude showed no difference between swallowing and tongue movements, either at face/tongue SMI or at SMA, whereas postmovement potential (PMP) was significantly larger in tongue protrusion than in swallowing only at face/tongue SMI. BP occurred earlier in swallowing than in tongue protrusion. Comparison between face/tongue SMI and SMA did not show any difference with regard to BP and PMP amplitude or BP onset time in either task. The preparatory role of the cerebral cortex in swallowing was similar to that in tongue movement, except for earlier activation in swallowing. Postmovement processing of swallowing was lesser than that of tongue movement in face/tongue SMI; probably suggesting that the cerebral cortex does not play a significant role in postmovement processing of swallowing. SMA plays a supplementary role to face/tongue SMI both in swallowing and tongue movements.     

Gravity sensing and signaling

Gravitropism has attracted much attention from plant biologists. Recent studies have provided molecular evidence supporting two long-surviving hypotheses about the mechanism of gravitropism: the starch-statolith hypothesis and the Cholodney-Went hypothesis. Amyloplast movement along the gravity vector within gravity-sensing cells in the root and shoot is the most likely trigger of subsequent intracellular signaling. Several possible events leading from this signaling to differential auxin distribution within the sensing cells have been suggested recently.     

Cell-passage activity is required for the malarial parasite to cross the liver sinusoidal cell layer

Liver infection is an obligatory step in malarial transmission, but it remains unclear how the sporozoites gain access to the hepatocytes, which are separated from the circulatory system by the liver sinusoidal cell layer. We found that a novel microneme protein, named sporozoite microneme protein essential for cell traversal (SPECT), is produced by the liver-infective sporozoite of the rodent malaria parasite, Plasmodium berghei. Targeted disruption of the spect gene greatly reduced sporozoite infectivity to the liver. In vitro cell invasion assays revealed that these disruptants can infect hepatocytes normally but completely lack their cell passage ability. Their apparent liver infectivity was, however, restored by depletion of Kupffer cells, hepatic macrophages included in the sinusoidal cell layer. These results show that malarial sporozoites access hepatocytes through the liver sinusoidal cell layer by cell traversal motility mediated by SPECT and strongly suggest that Kupffer cells are main routes for this passage. Our findings may open the way for novel malaria transmission-blocking strategies that target molecules involved in sporozoite migration to the hepatocyte.     

Streptococcal preparation OK-432: a new maturation factor of monocyte-derived dendritic cells for clinical use

For vaccinations based on dendritic cells (DCs), maturation of DCs is critical to the induction of T-cell responses. We tested the efficacy of streptococcal preparation OK-432 as a Good Manufacturing Practice (GMP)-grade maturation agent. OK-432 is currently used in Japan as a cancer immunotherapy drug. Immature monocyte-derived dendritic cells (imMo-DCs) isolated from human peripheral blood monocytes stimulated with granulocyte-macrophage colony stimulating factor and interleukin-4 were exposed to maturation factors, i.e., lipopolysaccharide (LPS), tumor necrosis factor alpha (TNF-alpha) plus prostaglandin E2 (PGE2), and OK-432 for 2 days. OK-432 increased expression of activation- and maturation-related molecules such as HLA-DR, CD80, CD83, and CD86 in imMo-DCs at levels similar to that of TNF-alpha plus PGE2, and higher than that of LPS. All agents examined induced allogeneic T-cell proliferation at a similar level. Only OK-432 caused significant production of interleukin-12 (IL-12) p70 and interferon gamma (IFN-gamma) at both the mRNA and protein levels in imMo-DCs. Neutralizing antibody against IL-12 p70 blocked IFN-gamma secretion from OK-432-stimulated Mo-DCs. IL-12 p70 produced by OK-432-stimulated imMo-DCs induced secretion of IFN-gamma by CD4+ T cells. OK-432 and LPS activated nuclear factor kappa B (NF-kappaB) in imMo-DCs. Both secretion of IL-12 p70 and IFN-gamma and activation of NF-kappaB induced by OK-432 were suppressed when imMo-DCs were pretreated with cytochalasin B. These results indicate that uptake of OK-432 by imMo-DCs is an early critical event for IL-12 p70 production and that NF-kappaB activation induced by OK-432 also contributes partially to IL-12 p70 production. In conclusion, OK-432 is a GMP-grade maturation agent and may be a potential tool for DC-based vaccine therapies.