Wettability, polarity and water absorption of Quercus ilex leaves: effect of leaf side and age

Plant trichomes play important protective functions and may have a major influence on leaf surface wettability. With the aim of gaining insight into trichome structure, composition and function in relation to water-plant surface interactions, we analyzed the adaxial and abaxial leaf surface of Quercus ilex L. (holm oak) as model. By measuring the leaf water potential 24 h after the deposition of water drops on to abaxial and adaxial surfaces, evidence for water penetration through the upper leaf side was gained in young and mature leaves. The structure and chemical composition of the abaxial (always present) and adaxial (occurring only in young leaves) trichomes were analyzed by various microscopic and analytical procedures. The adaxial surfaces were wettable and had a high degree of water drop adhesion in contrast to the highly unwettable and water repellent abaxial holm oak leaf sides. The surface free energy, polarity and solubility parameter decreased with leaf age, with generally higher values determined for the abaxial sides. All holm oak leaf trichomes were covered with a cuticle. The abaxial trichomes were composed of 8% soluble waxes, 49% cutin, and 43% polysaccharides. For the adaxial side, it is concluded that trichomes and the scars after trichome shedding contribute to water uptake, while the abaxial leaf side is highly hydrophobic due to its high degree of pubescence and different trichome structure, composition and density. Results are interpreted in terms of water-plant surface interactions, plant surface physical-chemistry, and plant ecophysiology

A Splicing Mutation in the Novel Mitochondrial Protein DNAJC11 Causes Motor Neuron Pathology Associated with Cristae Disorganization, and Lymphoid Abnormalities in Mice

Mitochondrial structure and function is emerging as a major contributor to neuromuscular disease, highlighting the need for the complete elucidation of the underlying molecular and pathophysiological mechanisms. Following a forward genetics approach with N-ethyl-N-nitrosourea (ENU)-mediated random mutagenesis, we identified a novel mouse model of autosomal recessive neuromuscular disease caused by a splice-site hypomorphic mutation in a novel gene of unknown function, DnaJC11. Recent findings have demonstrated that DNAJC11 protein co-immunoprecipitates with proteins of the mitochondrial contact site (MICOS) complex involved in the formation of mitochondrial cristae and cristae junctions. Homozygous mutant mice developed locomotion defects, muscle weakness, spasticity, limb tremor, leucopenia, thymic and splenic hypoplasia, general wasting and early lethality. Neuropathological analysis showed severe vacuolation of the motor neurons in the spinal cord, originating from dilatations of the endoplasmic reticulum and notably from mitochondria that had lost their proper inner membrane organization. The causal role of the identified mutation in DnaJC11 was verified in rescue experiments by overexpressing the human ortholog. The full length 63 kDa isoform of human DNAJC11 was shown to localize in the periphery of the mitochondrial outer membrane whereas putative additional isoforms displayed differential submitochondrial localization. Moreover, we showed that DNAJC11 is assembled in a high molecular weight complex, similarly to mitofilin and that downregulation of mitofilin or SAM50 affected the levels of DNAJC11 in HeLa cells. Our findings provide the first mouse mutant for a putative MICOS protein and establish a link between DNAJC11 and neuromuscular diseases

Characterization of a Mesorhizobium loti α-Type Carbonic Anhydrase and Its Role in Symbiotic Nitrogen Fixation▿

Carbonic anhydrase (CA) (EC 4.2.1.1) is a widespread enzyme catalyzing the reversible hydration of CO2 to bicarbonate, a reaction that participates in many biochemical and physiological processes. Mesorhizobium loti, the microsymbiont of the model legume Lotus japonicus, possesses on the symbiosis island a gene (msi040) encoding an α-type CA homologue, annotated as CAA1. In the present work, the CAA1 open reading frame from M. loti strain R7A was cloned, expressed, and biochemically characterized, and it was proven to be an active α-CA. The biochemical and physiological roles of the CAA1 gene in free-living and symbiotic rhizobia were examined by using an M. loti R7A disruption mutant strain. Our analysis revealed that CAA1 is expressed in both nitrogen-fixing bacteroids and free-living bacteria during growth in batch cultures, where gene expression was induced by increased medium pH. L. japonicus plants inoculated with the CAA1 mutant strain showed no differences in top-plant traits and nutritional status but consistently formed a higher number of nodules exhibiting higher fresh weight, N content, nitrogenase activity, and δ13C abundance. Based on these results, we propose that although CAA1 is not essential for nodule development and symbiotic nitrogen fixation, it may participate in an auxiliary mechanism that buffers the bacteroid periplasm, creating an environment favorable for NH3 protonation, thus facilitating its diffusion and transport to the plant. In addition, changes in the nodule δ13C abundance suggest the recycling of at least part of the HCO3− produced by CAA1

Complete rescue of the <i>DnaJC11^spc/spc</i> phenotype through expression of the human <i>DnaJC11</i> gene.

<p>(A) Schematic representation of the human BAC clone fragment that was used for the generation of Tg<i>huDnaJC11</i> mice. Genes and their orientation are indicated as well as NotI sites that were used for digestion. Horizontal line and number below represent the fragment length. (B) Copy number determination, by qPCR, of three transgenic lines, TgF843, TgF867, and TgF869 (n = 5-9 per group) using a primer pair common for both mouse and human <i>DnaJC11</i> genes. WT mice were considered to carry 2 copies of <i>DnaJC11</i>. (C) Body weight and (D) grip strength (normalized to body weight) curves for the indicated genotypes. All mice used were sex matched littermates, (n = 8). (E) Rescue of the thymic hypoplasia shown as total thymic cellularity, (n = 3). (F) Restoration of thymic subpopulations distribution in rescued mice (n = 3) as determined by flow cytometry after staining with antibodies against CD4 and CD8. Statistical analysis between controls and rescued (Tg/<i>DnaJC11^spc/spc</i>) mice is indicated. DP, double positive; DN, Double Negative. (G) Restoration of splenic subpopulations distribution in rescued mice. B cells and myeloid cells were defined as the ones positive for markers B220 and CD11b respectively, (n = 3). (H) Restoration of the leucopenia phenotype and the increased red blood cell phenotype in rescued mice (n = 3). Data represent means ± SE.</p

Lymphoid and blood abnormalities in <i>spc</i> mice.

<p>(A) Representative thymi dissected from <i>spc/spc</i> and WT (+/+) littermate mice at 4 weeks of age. Scalebar, 5mm. (B) Representative H/E stained thymic sections from <i>spc/spc</i> and +/+ littermate mice (n = 4). Scalebar, 400 µm. (C) Total thymus cellularity in <i>spc/spc</i> mice and control littermates, (n = 14 per group). (D) Percentage of thymic subpopulations in <i>spc/spc</i> mice and control littermates as determined by flow cytometry after staining of thymocytes with antibodies against CD4 and CD8. Data represent means ± SE from four independent experiments, (n = 13 per group). (E) Percentages of CD4^-CD8^- double negative (DN) subpopulations as determined by flow cytometry after staining of thymocytes with antibodies against CD25 and CD44, in <i>spc/spc</i> and control littermates, (n = 6 per group). (F) Representative spleens dissected from <i>spc/spc</i> and +/+ littermate mice at 4 weeks of age. Scalebar, 5 mm. (G) Total spleen cellularity of <i>spc/spc</i> mice and control littermates, (n = 14 per group). (H) Percentage of splenic subpopulations in <i>spc/spc</i> mice and control littermates as determined by flow cytometry using antibodies against CD4, CD8, B220 (B cells), Gr1 and CD11b (Myeloid). Data represent means ± SE from four independent experiments, (n = 10 per group). (I) Peripheral blood counts of <i>spc/spc</i> mice and control littermates, (n = 7 per group). Controls presented in bar graphs are healthy littermates (+/+ and <i>+/spc</i>).</p