Formation of a Tree having a Low Lignin Content

Received 30 September 2001/ Accepted in revised form 26 October 2001     

A 5-bp Insertion in Mip Causes Recessive Congenital Cataract in KFRS4/Kyo Rats

We discovered a new cataract mutation, kfrs4, in the Kyoto Fancy Rat Stock (KFRS) background. Within 1 month of birth, all kfrs4/kfrs4 homozygotes developed cataracts, with severe opacity in the nuclei of the lens. In contrast, no opacity was observed in the kfrs4/+ heterozygotes. We continued to observe these rats until they reached 1 year of age and found that cataractogenesis did not occur in kfrs4/+ rats. To define the histological defects in the lenses of kfrs4 rats, sections of the eyes of these rats were prepared. Although the lenses of kfrs4/kfrs4 homozygotes showed severely disorganised fibres and vacuolation, the lenses of kfrs4/+ heterozygotes appeared normal and similar to those of wild-type rats. We used positional cloning to identify the kfrs4 mutation. The mutation was mapped to an approximately 9.7-Mb region on chromosome 7, which contains the Mip gene. This gene is responsible for a dominant form of cataract in humans and mice. Sequence analysis of the mutant-derived Mip gene identified a 5-bp insertion. This insertion is predicted to inactivate the MIP protein, as it produces a frameshift that results in the synthesis of 6 novel amino acid residues and a truncated protein that lacks 136 amino acids in the C-terminal region, and no MIP immunoreactivity was observed in the lens fibre cells of kfrs4/kfrs4 homozygous rats using an antibody that recognises the C- and N-terminus of MIP. In addition, the kfrs4/+ heterozygotes showed reduced expression of Mip mRNA and MIP protein and the kfrs4/kfrs4 homozygotes showed no expression in the lens. These results indicate that the kfrs4 mutation conveys a loss-of-function, which leads to functional inactivation though the degradation of Mip mRNA by an mRNA decay mechanism. Therefore, the kfrs4 rat represents the first characterised rat model with a recessive mutation in the Mip gene.     

An 83-kDa embryonic-type nuclear antigen is detected within the germinal vesicles of oocytes of the ascidianHalocynthia roretzi

Summary Monoclonal antibodies were raised against germinal vesicles which were isolated from fully grown oocytes of the ascidianHalocynthia roretzi. Immunoblot analyses revealed that one of the antibodies, designated Hgv-2, recognized a single band with a molecular weight of about 83 kDa. The antibody, visualized by indirect immunohistochemistry, reacted only with the germinal vesicles of oocytes and did not react with test cells, follicle cells, and other somatic cells of the gonad. During embryogenesis the antigenicity was found in interphase nuclei of all embryonic cells. The antibody did not react with chromosomes or the mitotic apparatus. The antigenicity was retained by interphase nuclei of larval cells, but it disappeared from nuclei of juveniles about 7 days after metamorphosis.     

Selective production of glutamate by an immobilized marine blue-green alga,Synechococcus sp.

Summary Among 200 strains of marine bluegreen algae isolated from the coastal areas of Japan, the marine blue-green alga Synechococcus sp. NKBG 040607 excreted glutamate at the highest rate, 82.6% of total amino acids production being glutamate. Synechococcus sp. NKBG 40607 was immobilized in calcium alginate gel. Glutamate production by immobilized cells was double that of native cells. Maximal glutamate production (25 g/cm³ gel per day) of the immobilized cells was observed under a light intensity of 144 Einstein/m² per second at a cell concentration of 7.5 mg dry cells/cm³ gel. Immobilized cells of Synechococcus sp. can use nitrate as a nitrogen source. Immobilized marine Synechococcus sp. produced 0265 mg/cm³ gel of glutamate for 7 days in the presence of chloramphenicol.     

Respiration-Dependent Proton and Sodium Pumps in a Psychrophilic Bacterium, Vibrio sp. Strain ABE-1

Respiration-dependent proton and sodium flows in a psychrophilicbacterium, Vibrio sp. strain ABE-1, were examined. At alkalinepH, this bacterium grew without being affected by a proton conductor,carbonylcyanide m-chlorophenylhydrazone (CCCP). O₂-pulse intoanaerobic cell suspensions prepared with Na^$-free buffers inducedtransient alkalization in the presence of CCCP and acidificationat pH 8.5 and 6.5, respectively. However, using cells preparedwith Na^$-containing buffer, the transient pH changes of thecell suspension could be simultanously detected at both pHs.Several inhibitory experiments suggested that the acidificationand alkalization should be attributed to a respiration-dependentprimary H^$ pump and Na^$ pump, respectively, and that the latterwas similar to that first reported in a marine bacterium, Vibrioalginolyticus. This Na^$ pump may have supported the CCCP-resistantgrowth at alkaline pH. The H^$ and Na^$ pumps operated very actively at low temperatures,such as 5?C, and should markedly help sustain bacterial growthat low temperatures. (Received May 30, 1987; Accepted November 13, 1987)     

Chest wall and respiratory system mechanics in cats: effects of flow and volume

The effects of inspiratory flow rate and inflation volume on the resistive properties of the chest wall were investigated in six anesthetized paralyzed cats by use of the technique of rapid airway occlusion during constant flow inflation. This allowed measurement of the intrinsic resistance (Rw,min) and overall dynamic inspiratory impedance (Rw,max), which includes the additional pressure losses due to time constant inequalities within the chest wall tissues and/or stress adaptation. These results, together with our previous data pertaining to the lung (Kochi et al., J. Appl. Physiol. 64: 441-450, 1988), allowed us to determine Rmin and Rmax of the total respiratory system (rs). We observed that 1) Rw,max and Rrs,max exhibited marked frequency dependence; 2) Rw,min was independent of flow (V) and inspired volume (delta V), whereas Rrs,min increased linearly with V and decreased with increasing delta V; 3) Rw,max decreased with increasing V, whereas Rrs,max exhibited a minimum value at a flow rate substantially higher than the resting range of V; 4) both Rw,max and Rrs,max increased with increasing delta V. We conclude that during resting breathing, flow resistance of the chest wall and total respiratory system, as conventionally measured, includes a significant component reflecting time constant inequalities and/or stress adaptation phenomena.