Mapping of the K(+)/Na (+) discrimination locus Kna1 in wheat

In saline environments, bread wheat, Triticum aestivum L. (genomes AABBDD), accumulates less Na(+) and more K(+) in expanding and young leaves than durum wheat, T. turgidum L. (genomes AABB). Higher K(+)/Na(+) ratios in leaves of bread wheat correlate with its higher salt tolerance. Chromosome 4D from bread wheat was shown in previous work to play an important role in the control of this trait and was recombined with chromosome 4B in the absence of the Ph1 locus. A population of plants disomic for 4D/4B recombined chromosomes in the genetic background of T. turgidum was developed to investigate the genetic control of K(+)/Na(+) discrimination by chromosome 4D. Evidence was obtained that the trait is controlled by a single locus, designated Kna1, in the long arm of chromosome 4D. In the present work, K(+)/Na(+) discrimination was determined for additional families with 4D/4B chromosomes. The concentrations of Na(+) and K(+)/Na(+) ratios in the youngest leaf blades clustered in two nonoverlapping classes, and all recombinant families could be unequivocally assigned to Kna1 and kna1 classes. The Kna1 locus scored this way was mapped on a short region in the 4DL arm and was completely linked to Xwg199, Xabc305, Xbcd.402, Xpsr567, and Xpsr375; it was also mapped as a quantitative trait. The results of the QTL analysis, based on the K(+)/Na(+) ratios in the young leaves of greenhousegrown plants and flag leaves of field-grown plants, agreed with the position of Knal determined as a qualitative trait. Several aspects of gene introgression by manipulation of the Ph1 locus are discussed.

Parathyroid hormone mRNA levels are increased by progestins and vary during rat estrous cycle

Estrogen increases parathyroid hormone (PTH) mRNA levels in vivo in ovariectomized rats. We now show that the 19-norprogestin R-5020 given to weanling rats or mature ovariectomized rats led to a twofold increase in thyroparathyroid PTH mRNA levels. This increase in PTH mRNA occurred at 24 and 48 h after progesterone but not at 72 h. There were no changes in serum calcium. In vitro, in primary cultures of bovine parathyroid cells, progesterone increased PTH mRNA levels threefold at 10(-8) M and twofold at 10(-9) M after 24 h. Progesterone receptor (PR) mRNA was demonstrated in rat parathyroid tissue by in situ hybridization and in human parathyroid adenoma by immunohisto-chemistry. Changes in PTH mRNA levels during the rat estrous cycle were also studied. At proestrus and estrus PTH mRNA levels were increased significantly by three- and fourfold compared with diestrus. Our results confirm that the parathyroid gland is a target organ for the ovarian sex steroids estrogen and progesterone and are of physiological relevance as shown by the changes during estrus.

New insights into the regulation of parathyroid hormone synthesis and secretion in chronic renal failure

The main factors which regulate parathyroid hormone (PTH) production are calcium, phosphate, vitamin D and the sex steroids, estrogens and progestagins. Hypocalcaemia leads to increased PTH secretion in seconds and minutes, gene expression in hours and parathyroid cell number in weeks and months. Hypercalcaemia leads to a decrease in PTH secretion by its action on the parathyroid cell calcium receptor and no decrease in PTH mRNA concentrations. There is now convincing evidence that phosphate regulates the parathyroids independent of its effect on serum calcium and 1,25-dihydroxyvitamin D3. (1,25(OH)2D3). In vivo in rats hypophosphataemia markedly decreases PTH mRNA and serum PTH independent of its effect on serum calcium and 1,25(OH)2D3. Clinical studies also indicate that phosphate regulates the parathyroids independent of its effect on serum calcium and 1,25(OH)2D3 1,25(OH)2D3 itself has a marked effect on the parathyroids where it decreases PTH gene transcription by a direct action. Parathyroid cell proliferation is regulated by dietary calcium and phosphate with hypocalcaemia markedly increasing and hypophosphataemia markedly decreasing the number of proliferating cells. The application of basic science findings of how calcium, phosphate and 1,25(OH)2D3 regulate the parathyroids has led to an efficient and safe prescription for the management of the secondary hyperparathyroidism of chronic renal failure which is the maintenance of a normal serum calcium and phosphate and the careful use of bolus doses of 1,25(OH)2D3.

Narrowing of the Hailey-Hailey disease gene region on chromosome 3q and identification of one kindred with a deletion in this region

Hailey-Hailey disease is a cutaneous abnormality transmitted as an autosomal dominant trait in which impaired interkeratinocyte adhesion produces recurrent blisters in characteristic skin sites. We report here a confirmation of the initial mapping of the mutant gene to chromosome 3q in an additional seven kindreds, narrowing of the candidate region to the sequences flanked by D3S1589 and D3S1541, and the finding in one family of a genomic DNA deletion whose centromeric end is located between these two flanking markers.

Photosynthesis, inorganic plant nutrition, solutions, and problems

A brief account is given of the research that D.I. Arnon did before he ventured into the field of photosynthesis, viz. his work on inorganic plant nutrition in the laboratory of D.R. Hoagland. The connection between the two areas is indicated. In his work on plant nutrition Dr Arnon emphasized the role of specific nutrients and, with P.R. Stout, formulated a definition of essentiality that is used to this day. It is now necessary, however, to take into account elements not meeting their criteria of essentiality, as shown by a consideration of the element silicon.

Differential Solute Regulation in Leaf Blades of Various Ages in Salt-Sensitive Wheat and a Salt-Tolerant Wheat x Lophopyrum elongatum (Host) A. Love Amphiploid

Leaf blades of different ages from a salt-tolerant wheat x Lophopyrum elongatum (Host) A. Love (syn. Agropyron elongatum Host) amphiploid and its salt-sensitive wheat parent (Triticum aestivum L.cv Chinese Spring) were compared for their ionic relations, organic solute accumulation, and sap osmotic potential ([pi]sap). The plants were grown for 18 d in nonsaline (1.25 mM Na+) and salinized (200 mM NaCl) nutrient solutions. The response of leaf blades to NaCl salinity depended greatly on their age or position on the main stem. Na and proline levels were highest in the oldest leaf blade and progressively lower in younger ones. Glycine betaine and asparagine levels were highest in the youngest blade. The [pi]sap was similar for corresponding leaf blades of both genotypes, but contributions of various solutes to the difference in [pi]sap between blades from control and 200 mM NaCl treatments differed greatly. The NaCl-induced decline in [pi]sap of the youngest leaf blade of Chinese Spring was predominately due to the accumulation of Na and to a lesser extent asparagine; in the amphiploid, it was due to a combination of glycine betaine, K, Na, and asparagine. Proline contributed little in the youngest blade of either genotype. In the older blades Na was the major solute contributing to the decline in [pi]sap. Thus, the maintenance of low Na and high K levels and the accumulation of glycine betaine in the young leaf tissues contributed to the NaCl tolerance of the amphiploid. No such role was evident for proline.

Oestrogens and calcium regulatory hormones: potential implications for bone

Postmenopausal oestrogen deficiency is associated with the development of osteoporosis. Oestrogen therapy prevents further bone loss but does not have an anabolic effect. The only treatment with an anabolic effect on bone is intermittent parathyroid hormone treatment. Oestrogens have a direct action on the parathyroid to increase parathyroid hormone gene expression and parathyroid hormone secretion. They exert this effect at doses that are too low to cause the uterotrophic effect of oestradiol. Osteoporotic patients have a decreased parathyroid hormone secretory response to changes in serum calcium, supporting the experimental data that oestrogens have a direct effect on the parathyroid. The value of parathyroid hormone treatment is limited by the need for parenteral therapy. The ability of oestrogens to increase parathyroid hormone secretion suggests that the intermittent administration of oestrogen analogues, at doses that exert no effects on breast tissue and the uterus, would be the optimal treatment for osteoporosis.

New aspects in the control of parathyroid hormone secretion

Ca2+ binds to a parathyroid cell Ca2+ receptor, which is G protein-coupled and activates inositol triphosphate production. Mutations in the Ca(2+)-sensing receptor gene cause familial hypocalciuric hypercalcemia and neonatal severe hyperparathyroidism. Chronic hypocalcemia increases parathyroid hormone messenger RNA levels and parathyroid cell hyperplasia. Parathyroid cells in vitro are heterologous in their response to Ca2+. The concept of a higher Ca2+ set-point in secondary hyperparathyroidism is controversial. Calcitriol is more effective than the less hypercalcemia analogues in decreasing parathyroid hormone messenger RNA and immunoreactive parathyroid hormone levels, and its kinetics are well established. Phosphate and estrogens regulate the parathyroid independently of 1,25 dihydroxyvitamin D3 and Ca2+. The physiology of the effects of endothelin and insulin-like growth factors on the parathyroid need to be established. Important advances are being made in understanding the regulation of parathyroid hormone synthesis and secretion, which are relevant to both normal physiology and the pathogenesis and treatment of diseases such as the secondary hyperparathyroidism of renal failure and osteoporosis.

Recalling basal cell carcinoma patients. A regional survey

BACKGROUND

Patients with a basal cell carcinoma (BCC) are at increased risk for developing further BCCs, and long-term follow-up has been recommended to detect new cancers at an earlier, more easily treatable stage. The majority of BCCs are treated by dermatologists in their offices; we do not know to what extent they perform long-term follow up on their patients.

OBJECTIVE

To determine how practicing dermatologists follow up their BCC patients.

METHODS

A mailed questionnaire survey of 166 practicing members of a regional dermatologic society (the San Francisco Dermatological Society), to which 142 (85%) replied.

RESULTS

Two thirds of the respondents recalled BCC patients for screening examinations; of these, 58% followed up non-responders. Recall efforts were hampered by inefficient, unwieldy, and time-consuming techniques.

CONCLUSION

Practicing dermatologists are motivated to recall BCC patients for examination, but guidelines and techniques for effective and efficient computerized recalling of skin cancer patients are needed. It is suggested that the American Academy of Dermatology set up a task force to develop guidelines and criteria for effective recall software.

The anomaly of silicon in plant biology

Silicon is the second most abundant element in soils, the mineral substrate for most of the world's plant life. The soil water, or the "soil solution," contains silicon, mainly as silicic acid, H4SiO4, at 0.1-0.6 mM--concentrations on the order of those of potassium, calcium, and other major plant nutrients, and well in excess of those of phosphate. Silicon is readily absorbed so that terrestrial plants contain it in appreciable concentrations, ranging from a fraction of 1% of the dry matter to several percent, and in some plants to 10% or even higher. In spite of this prominence of silicon as a mineral constituent of plants, it is not counted among the elements defined as "essential," or nutrients, for any terrestrial higher plants except members of the Equisitaceae. For that reason it is not included in the formulation of any of the commonly used nutrient solutions. The plant physiologist's solution-cultured plants are thus anomalous, containing only what silicon is derived as a contaminant of their environment. Ample evidence is presented that silicon, when readily available to plants, plays a large role in their growth, mineral nutrition, mechanical strength, and resistance to fungal diseases, herbivory, and adverse chemical conditions of the medium. Plants grown in conventional nutrient solutions are thus to an extent experimental artifacts. Omission of silicon from solution cultures may lead to distorted results in experiments on inorganic plant nutrition, growth and development, and responses to environmental stress.

Short-term experiments on ion transport by seedlings and excised roots : technique and validity

The absorption of K(+) by excised roots of barley (Hordeum vulgare L. cv California Mariout) has been systematically compared with that of entire, undisturbed seedlings. Some experiments have also been done with wheat (Triticum aestivum L.) and an amphiploid obtained from a cross between it and salt-tolerant tall wheatgrass (Lophopyrum elongatum Host Löve [syn. Agropyron elongatum Host]). For all three genotypes, the rate of K(+) absorption measured in a 20-min period was identical for entire 8-d-old seedlings and their excised roots within the experimental error. Manipulation gentler than root excision, viz. careful transfer of seedlings from one experimental solution to another, was also without effect on the rate of K(+) absorption. Absorption of K(+) measured by assay of its (86)Rb label in the tissue was identical with that measured by K(+) depletion of the experimental solutions assayed chemically. For the plant materials and conditions of these experiments, the excised root technique for studying ion transport into roots is validated. The advantages of the technique, and findings differing from the present ones, are discussed.

Salt tolerance and ionic relations of wheat as affected by individual chromosomes of salt-tolerant Lophopyrum elongatum

Bread wheat cv. Chinese Spring (CS), an amphiploid from a cross between CS and salt-tolerant Lophopyrum (= Agropyron) elongatum (Host) Löve, 19 of 21 possible disomic substitution lines of L. elongatum chromosomes for CS homoeologues, and a check cultivar, PI 178704, were grown in a replicated field trial under two levels of salinity and control conditions. Under salinity, the amphiploid greatly outperformed CS in grain yield, biomass, and other characters, indicating that it is more salt tolerant than CS. Of the seven L. elongatum chromosomes, six increased salt tolerance in disomic substitution lines; the most dramatic increase was conferred by chromosome 3E. Increased salt tolerance of the amphiploid was associated with the exclusion of Na+ and Cl− and inclusion of K+ as well as retranslocation of K+. Lophopyrum chromosomes controlling these physiological characters were identified. Some of the chromosomes had multiple effects, where as others affected only a specific character. The largest effects were associated with chromosome 3E. In addition, several wheat chromosomes controlled the exclusion or inclusion of these ions; the most notable effects were by chromosome 4D. Salt tolerance correlated negatively with Na+ and positively with K+ concentration in the flag leaf and with the K+/Na+ ratios. The relationships were strong enough to be exploited as selection tools in the breeding of salt-tolerant wheat cultivars.Key words: salt tolerance, wheat, Lophopyrum elongatum.

Occurrence and in Vivo Biosynthesis of Indole-3-Butyric Acid in Corn (Zea mays L.)

Indole-3-butyric acid (IBA) was identified as an endogenous compound in leaves and roots of maize (Zea mays L.) var Inrakorn by thin layer chromatography, high-performance liquid chromatography, and gas chromatography-mass spectrometry. Its presence was also confirmed in the variety Hazera 224. Indole-3-acetic acid (IAA) was metabolized to IBA in vivo by seedlings of the two maize varieties. The reaction product was identified by thin layer chromatography, high performance liquid chromatography, and gas chromatography-mass spectrometry after incubating the corn seedlings with [(14)C]IAA and [(13)C(6)]IAA. The in vivo conversion of IAA to IBA and the characteristics of IBA formation in two different maize varieties of Zea mays L. (Hazera 224 and Inrakorn) were investigated. IBA-forming activity was examined in the roots, leaves, and coleoptiles of both maize varieties. Whereas in the variety Hazera 224, IBA was formed mostly in the leaves, in the variety Inrakorn, IBA synthesis was detected in the roots as well as in the leaves. A time course study of IBA formation showed that maximum activity was reached in Inrakorn after 1 hour and in Hazera after 2 hours. The pH optimum for the uptake of IAA was 6.0, and that for IBA formation was 7.0. The K(m) value for IBA formation was 17 micromolar for Inrakorn and 25 micromolar for Hazera 224. The results are discussed with respect to the possible functions of IBA in the plant.

Accidental intravascular injection during infiltration anesthesia of the skin

Accidental intravascular injection of lidocaine during the induction of infiltration anesthesia for dermatologic surgery is an occasional and harmless occurrence. The author noted nine such episodes in a three-year period of full-time private dermatologic practice. A very brief, sharp, stinging pain lasting only seconds and immediately followed by blanching in a vascular distribution characterized these episodes. The blanching, resulting from the 1:200,000 epinephrine solution used in the lidocaine solution usually disappeared within five to ten minutes. Patients experienced no ill effects. The standard textbooks and reviews caution practitioners to aspirate before injecting a local anesthetic; this is unnecessary when performing infiltration anesthesia of the skin.

Laboratory measurement of bilirubin

Several methods for determination of total bilirubin and its fractions have been critically discussed. Methods for serum determinations are summarized in Table 1. Because results of direct bilirubin cannot necessarily be equated with conjugated bilirubin, care must be taken in interpreting results from different laboratories, and clinicians are encouraged to become familiar with methods in use at their own institutions. Despite problems reported in the literature, bilirubin determinations, together with a reference range established for one's own patient population, should provide valuable information for patient management.

Primula contact dermatitis: an easily overlooked diagnosis

Contact dermatitis to Primula obconica is not uncommon in the United States, yet it is scarcely mentioned in current North American dermatologic textbooks and literature. Affecting mainly women, primula contact dermatitis is often misdiagnosed since its nondescript pattern suggests an endogenous dermatitis. The author summarizes his experience with nine patients encountered in his practice during two years. Patch testing is important since a positive patch test reaction confirms the diagnosis and helps to convince the patient to discard the offending plant(s). A simple technique of patch testing with the primula leaf is described.

Selective accumulation of lymphocyte precursor cells mediated by stromal cells of hemopoietic origin

Thymocytes were propagated in long-term cultures supported by stromal cells of both bone marrow and thymus origin. Interleukin 2 (IL-2) supplementation augmented the cell yield and allowed detailed phenotype analysis. Within 2-3 months of culture a cell population was selected in which the expression of Thy-1 antigen persisted, CD4 and CD8 antigens gradually declined, and Pgp-1 antigen, found on less than 5% of fresh thymocytes, was strongly increased. This cultured cell population (Thy-1.2 origin) contained no detectable spleen colony-forming units (CFU-S) but efficiently repopulated the thymus of Thy-1.1-irradiated congenic mice, indicating the precursor T-cell nature of the population. Upon removal from the stroma, the T cells exhibited poor cytotoxicity towards syngeneic tumor cells. Further propagation with IL-2 in the absence of stroma resulted in the acquisition of cytotoxic ability. Replacement of the horse serum used in the above experiments with fetal calf serum resulted in accumulation of cells expressing B220 antigen. This experimental model provides the means to maintain lymphocyte precursor cells in long-term culture and to further study their differentiation in the absence of stroma, both in vitro and in vivo.

In vivo 23Na and 31P NMR measurement of a tonoplast Na+/H+ exchange process and its characteristics in two barley cultivars

A Na+ uptake-associated vacuolar alkalinization was observed in roots of two barley cultivars (Arivat and the more salt-tolerant California Mariout) by using 23Na and 31P in vivo NMR spectroscopy. A NaCl uptake-associated broadening was also noted for both vacuolar Pi and intracellular Na NMR peaks, consistent with Na+ uptake into the same compartment as the vacuolar Pi. A close coupling of Na+ with H+ transport (presumably the Na+/H+ antiport) in vivo was evidenced by qualitative and quantitative correlations between Na+ accumulation and vacuolar alkalinization for both cultivars. Prolongation of the low NaCl pretreatment (30 mM) increased the activity of the putative antiport in Arivat but reduced it in California Mariout. This putative antiport also showed a dependence on NaCl concentration for California Mariout but not for Arivat. No cytoplasmic acidification accompanied the antiporter activity for either cultivar. The response of adenosine phosphates indicated that ATP utilization exceeded the capacity for ATP synthesis in Arivat, but the two processes seemed balanced in California Mariout. These comparisons provide clues to the role of the tonoplast Na+/H+ antiport and compensatory cytoplasmic adjustments including pH, osmolytes, and energy phosphates in governing the different salt tolerance of the two cultivars.

Characterization and Rooting Ability of Indole-3-Butyric Acid Conjugates Formed during Rooting of Mung Bean Cuttings

Indole-3-butyric acid (IBA) is rapidly metabolized by mung bean cuttings during rooting. Twenty-four hours after application, less than 20% of the applied IBA remained in the free form and its level decreased continuously in the later stages of rooting. Indole-3-butyrylaspartic acid (IBAsp) and at least two high molecular weight conjugates were the major metabolites in IBA-treated cuttings. In the latter conjugates, at least part of the IBA moiety is attached to a high molecular weight constituent in an amide linkage. IBAsp level peaked 24 hours after application of IBA to the cuttings and then declined. The level of the high molecular weight conjugates increased continuously throughout the rooting process. The conjugates were active in inducing rooting of cuttings, with IBAsp being superior to free IBA. It is suggested that IBA conjugates, and particularly IBAsp, serve as the source of auxin during the later stages of rooting.