The maize rough sheath2 gene and leaf development programs in monocot and dicot plants.

Leaves of higher plants develop in a sequential manner from the shoot apical meristem. Previously it was determined that perturbed leaf development in maize rough sheath2 (rs2) mutant plants results from ectopic expression of knotted1-like (knox) homeobox genes. Here, the rs2 gene sequence was found to be similar to the Antirrhinum PHANTASTICA (PHAN) gene sequence, which encodes a Myb-like transcription factor. RS2 and PHAN are both required to prevent the accumulation of knox gene products in maize and Antirrhinum leaves, respectively. However, rs2 and phan mutant phenotypes differ, highlighting fundamental differences in monocot and dicot leaf development programs.

The rough sheath2 gene negatively regulates homeobox gene expression during maize leaf development.

Leaves of higher plants are produced in a sequential manner through the differentiation of cells that are derived from the shoot apical meristem. Current evidence suggests that this transition from meristematic to leaf cell fate requires the down-regulation of knotted1-like homeobox (knox) gene expression. If knox gene expression is not repressed, overall leaf shape and cellular differentiation within the leaf are perturbed. In order to identify genes that are required for the aquisition of leaf cell fates, we have genetically screened for recessive mutations that confer phenotypes similar to dominant mutations (e.g. Knotted1 and Rough sheath1) that result in the ectopic expression of class I knox genes. Independently derived mutations at the rough sheath2 (rs2) locus condition a range of pleiotropic leaf, node and internode phenotypes that are sensitive to genetic background and environment. Phenotypes include dwarfism, leaf twisting, disorganized differentiation of the blade-sheath boundary, aberrant vascular patterning and the generation of semi-bladeless leaves. knox genes are initially repressed in rs2 mutants as leaf founder cells are recruited in the meristem. However, this repression is often incomplete and is not maintained as the leaf progresses through developement. Expression studies indicate that three knox genes are ectopically or over-expressed in developing primordia and in mature leaves. We therefore propose that the rs2 gene product acts to repress knox gene expression (either directly or indirectly) and that rs2 gene action is essential for the elaboration of normal leaf morphology.

Induction of leaves directly from leaves in the maize mutant Lax midrib1-O.

One of the several phenes specified by the maize dominant mutation Lax midrib1-O (Lxm1-O on 3L) is the proliferation of leaf "flaps" usually paired around veins on the abaxial leaf surface. Using histology and scanning electron microscopy, we show these flaps to be authentic leaf structures; in rare instances, complete ectopic leaves are found. The first divisions preceding flap emergence occur between plastochrons 4 and 7, stages when the course of leaf differentiation is well under way. No sign of meristem or any small, densely cytoplasmic primordium-like cells were seen at the sites of flap initiation. In addition, the sites of ectopic leaf initiation do not express KNOX (Knotted-like homeobox) proteins, a molecular marker for shoot apical meristem cell identity. Thus, the cells that proliferate into ectopic leaves do not arise from a meristem or a primordium. A similar phenomenon has been described in several dicots, but in no other monocots. The details of flap morphology compared to the morphology of the leaf proper suggest a model whereby cells in regions of the leaf proper maintain the competence they acquired in the meristem. These cells then respond properly, in a regulated manner, to a delayed signal emanating from veins denoting "make the organ you are competent to make."

The maize mutant narrow sheath fails to establish leaf margin identity in a meristematic domain.

The maize mutant narrow sheath (ns) displays a leaf shape and plant stature phenotype that suggests the preprimordial deletion of a leaf domain. The ns mutant phenotype is inherited as a recessive, duplicate-factor trait, conditioned upon homozygosity for each of the two unlinked mutations narrow sheath-1 (ns1) and narrow sheath-2 (ns2). Mutant leaves are missing a large domain including the leaf margin, and mutant internodes are shortened on the marginal side of the stem. This domain deletion extends from the internode to beyond the longitudinal mid-length of the blade, and corresponds to an alteration in the organization of a specific region of the shoot apical meristem. The premargin region of mutant founder cells fail to down-regulate expression of Knox genes, markers of nonleaf meristematic identity. Our results indicate that leaf domains may acquire identity in the meristem itself, and that the subdivision of preprimordial developmental fields into differential domains is a common feature of both plant and animal organogenesis.

Ectopic expression of the knox homeo box gene rough sheath1 alters cell fate in the maize leaf.

Rough sheath1 (Rs1) is a dominant mutation that alters cell fate and causes unregulated cell division and expansion in the maize leaf. A knox (Kn1 like-homeo box gene) sequence closely linked to the Rs1-O mutation was cloned and shown by transposon mutagenesis to encode the rs1 gene. The deduced amino acid sequence of the RS1 protein is highly similar to KN1 in the homeo domain but contains a unique amino-terminal region. rs1 is expressed in the shoot apical meristem in a circular pattern preceding leaf initiation, but is not detectable in leaf primordia or mature leaves in normal plants. Rings of rs1 expression subtend leaf insertion sites in the shoot, and lateral organ primordia in inflorescence and floral meristems. The timing and position of rs1 expression in meristems suggests a possible role for rs1 in patterning the placement of lateral organs along the axis of the shoot. In contrast to wild type, rs1 is expressed in early leaf primordia of Rs1 mutant plants, suggesting that ectopic expression causes the mutant phenotype. Ectopic expression in Rs1-O plants suggests the ligular [corrected] region is more competent to respond to rs1 than blade or sheath tissues.

[Itching following therapy with hydroxyethyl starch (HES) in otoneurological diseases]. / Juckreiz nach Therapie mit Hydroxyäthylstärke (HES) bei otoneurologischen Erkrankungen.

It is generally assumed, that a disturbance of microcirculation is the common pathogenetic end factor in various cochleovestibular disorders of different etiology. Therefore improvement of microcirculation is an important therapeutic goal. Several studies demonstrated, that hydroxyethylstarch (HES) has better haemorheological effects than Dextran and less side effects. For this reason we have changed the therapy with Dextran since 1987 to hydroxyethylstarch in several oto-neurological disorders (as sudden hearing loss, neuronopathia vestibularis, idiopathic facial palsy). As after the therapy with HES--generally after dismissal from the ENT-department--some patients complained of general pruritus, so we performed a retrospective study with a standardized interview-protocol. Of 481 treated patients we investigated 237 (49%): of 149 patients treated with HES 200/0.5, 43 patients (28.8%) complained of pruritus; from 88 patients treated with Dextran 40, only 5 patients (5.7%) reported pruritus. The difference is significant (p less than 0.0001). In nearly half of the patients (more than 40%) the pruritus started in normal skin 1 to 3 weeks after the HES-therapy and lasted for 6 weeks to 6 months; the itching was very resistant to therapy (f.e. with antihistaminics). We want to draw the attention to this possible, in the literature until now quite neglected, for some patients extremely uncomfortable and socially embarrassing side effects after HES-therapy when given in relatively high doses. It is therefore suggested therapeutic recommendations should be developed to prevent this undesired side effect.

Specific DNA alterations associated with the environmental induction of heritable changes in flax.

Several flax varieties have been shown to undergo environmentally induced heritable changes resulting in stable lines termed genotrophs. The most notable of these is the variety Stormont Cirrus, also termed "plastic" or Pl. A number of morphological, biochemical and genetic differences are associated with environmental induction of heritable changes in flax. We have studied 5S rDNA alterations as a model system for understanding environmental induction of heritable changes in flax. This paper reports the isolation of a flax 5S rRNA gene variant which identifies genotroph specific restriction fragment length polymorphisms (RFLPs) in flax. Restriction fragment patterns for several enzymes were observed in both large and small genotrophs which consistently differed from the progenitor, Stormont Cirrus. Identical RFLP profiles for all restriction endonucleases tested were observed in four small genotrophs produced from separate environmental induction experiments. Comparison between Stormont Cirrus and these small genotrophs showed at least six differing bands in addition to several high molecular weight polymorphisms. Genetic data indicate that the polymorphisms were all produced from a repetitive 5S rRNA gene cluster at a single chromosomal locus. Similar, but not identical, polymorphisms are also detected in other flax varieties and Linum species suggesting that the induced variation is related to that which occurs naturally. The results are evidence that a specific set of DNA alterations occur in association with the induction of heritable changes in flax. This is the first genetic marker which is altered to an identical state in one type of genotroph. The results are discussed with respect to mechanisms for environmentally induced heritable change in plants.

[Pruritus--a side effect of hydroxyethyl starch? First report]. / Juckreiz--Eine Nebenwirkung von Hydroxyäthylstärke (HES)? Erste Mitteilung.

It is generally assumed that a disturbance of microcirculation is the common pathogenic pathway of various cochleovestibular disorders. Several studies have demonstrated that hydroxyethyl starch (HES) has better rheological effects than dextran 40, and fewer side-effects. Therefore, we changed from dextran 40 to hydroxyethyl starch in 1987 for the treatment of several otoneurological disorders. However, some patients complained of general pruritus after 1 or 2 weeks of therapy with HES. Therefore, a retrospective study was performed using a questionnaire of 491 patients treated for various cochleovestibular disorders. We received answers from 94 (20%): 25 of 59 (42.4%) patients treated with HES complained of pruritus compared with only 4 of 35 (11.4%) patients treated with dextran 40. The difference was significant (P less than 0.01). Critical points are the retrospective study design and the small number of patients, so that no conclusions can be drawn about the incidence of pruritus after therapy with HES. However, we would like to focus attention on this side-effect, which has been neglected in the literature but is extremely uncomfortable and socially embarrassing for some patients.

Chromosomal and molecular analysis of 5S RNA gene organization in the flax, Linum usitatissimum.

The 5S rRNA genes (5S DNA) comprise up to 3% of the flax genome. Large copy-number changes in 5S DNA have been observed in flax genotrophs. We have characterized the chromosomal and molecular organization of this large gene family. In situ hybridization studies indicate the 5S DNA is distributed over many chromosomes, unlike most plants studied to date. Eleven genomic clones were isolated and characterized. All but one of the clones contain both 5S DNA and non-5S DNA. The homology of the 5S DNA of each clone, to a previously isolated flax 5S plasmid clone (pBG13), was determined. Five groups of 5S DNA were identified based on shared identity and repeat unit size. Group-1 and group-2 clones are the most abundant in terms of genomic representation. The remaining groups are significantly different from the previously described flax 5S DNA and are in low representation in comparison to group-1 and group-2 5S DNA. The results establish the presence of several groups of 5S DNA which are distributed over many chromosomes. The extent of identity shared among these groups to pBG13, indicates a high degree of divergence between the different groups.

[Chemical composition and biological quality of defatted hazelnut flour]. / Composición química y calidad biológica de harina desgrasada de avellana.

The results of the chemical composition and biological quality of deffated hazel nut flour are shown. The samples analyzed contained significant amounts of proteins (19%) comparable to legume flour, higher than cereals and lower than deffated oleaginous flours. The oil extracted from the seed was analyzed and the average results obtained were the following: Refraction index, 1.47; saponification No. 184.8; iodine No. 85.0. The average composition of the fatty acids obtained by gas liquid chromatography was: Palmitic acid 2.3% Palmitoleic acid 37.0% Stearic acid 0.5% Oleic acid 39.5% Linoleic acid 6.9% Linolenic acid 1.1% Eicosanoic acid 2.3% Eicosaenoic acid 4.6% Docosenoic acid 3.4% Tetraeicosanoic acid 0.3% These results indicate a good-quality oil due to the low content of linolenic acid. The nutritive value of the deffated meal measured in the rats gave a net protein ratio (NPR) of 3.58, lower than the corresponding casein value (4.10). The true protein digestibility measured in the rat gave a value of 7.3%, compared to 95% for casein. The amounts of iron and phosphorous are comparatively lower than those reported for rape-seed meal and sunflower meal.