Principles and strategies in breeding for higher salt tolerance

Summary Salinity is an environmental component that usually reduces yield. Recent advances in the understanding of salt effects on plants have not revealed a reliable physiological or biochemical marker that can be used to rapidly screen for salt tolerance. The necessity of measuring salt tolerance based upon growth in saline relative to non-saline environments makes salt tolerance measurements and selection for tolerance difficult. Additionally, high variability in soil salinity and environmental interactions makes it questionable whether breeding should be conducted for tolerance or for high yield. Genetic techniques can be used to identify the components of variation attributable to genotype and environment, and the extent of genetic variation in saline and nonsaline environments can be used to estimate the potential for improving salt tolerance. Absolute salt tolerance can be improved best by increasing both absolute yield and relative salt tolerance.     

Accumulation and Subcellular Localization of alpha-Galactosidase-Hemagglutinin in Developing Soybean Cotyledons

We have investigated the accumulation and intracellular localization of soybean (Glycine max [L.] Merr. cv Forrest) α-galactosidase-hemagglutinin during seed development. Cotyledon tissue was embedded in Lowicryl K4M and immunocytochemical localization was accomplished through treating thin sections with α-galactosidase antisera followed by indirect labeling with protein A coupled to colloidal gold. Gold particles were localized on the Golgi apparatus and protein bodies. We interpret this to indicate that α-galactosidase-hemagglutinin is transferred to and transported through the Golgi apparatus and finally deposited within the protein body by a Golgi apparatus-mediated process.     

Medullary expiratory activity: influence of intercostal tendon organs and muscle spindle endings

Studies were conducted to determine the effects of intercostal muscle spindle endings (MSEs) and tendon organs (TOs) on medullary expiratory activity in decerebrate cats. Impeded intercostal muscle contractions, elicited by electrical stimulation of the peripheral cut end of the T6 ventral root, were used to stimulate intercostal TOs without MSEs. Impeded contractions of the intercostal muscles augmented expiratory laryngeal motoneuron activity, and either had no effect on or reduced the activity of bulbospinal expiratory neurons. Vibration was used to stimulate intercostal MSEs. Intercostal MSEs had no effect on medullary expiratory neuron activity. It is concluded that both external and internal intercostal TOs have an excitatory effect on expiratory laryngeal motoneuron activity and an inhibitory effect on a subpopulation of expiratory neurons driving intercostal and/or abdominal muscles, and intercostal MSEs have no direct influence on medullary expiratory activity.     

Light-Sensitivity of Hazel Seeds with Respect to the Breaking of Dormancy

Light breaks the dormancy of hazel (Corylus avellana L.) seedswhen the testa is removed. Light, acting via phytochrome, alsopromotes the germination of hazel seeds when the embryonic axisis surgically uncovered. In such seeds with the axis uncoveredremoval of the testa is antagonistic to the light promotionof germination. (Received January 17, 1982; Accepted April 25, 1983)     

Dipstick haematuria and bladder cancer in men over 60: results of a community study.

OBJECTIVE--To investigate the prevalence and relevance of dipstick haematuria in a group of men in the community. DESIGN--Prospective study of elderly men invited to attend a health centre for urine screening as part of a health check. SETTING--An inner city health centre in Leeds. SUBJECTS--578 Of 855 men aged 60-85 responding to an invitation to participate. INTERVENTIONS--The subjects had their urine tested with a dipstick (Multistix) for the presence of blood and then tested their urine once a week for the next 10 weeks. Those with one or more positive test results were offered full urological investigation. MAIN OUTCOME MEASURE--The prevalence of urological disease in those subjects with dipstick haematuria. RESULTS--78 Men (13%) had dipstick haematuria on a single test and a further 54 (9%) had evidence of dipstick haematuria when testing their urine once a week during a subsequent 10 week period. Investigation of 87 men disclosed urological disease in 45, including four with a bladder tumour and seven with epithelial dysplasia. CONCLUSION--Dipstick haematuria is a common incidental finding in men over 60 and is associated with appreciable urological disease. The introduction of less invasive methods of investigation, particularly flexible cystoscopy and ultrasonography, has made investigation of these patients simple and safe and makes screening for bladder cancer in the community more feasible.     

Analysis of E1A-mediated growth regulation functions: binding of the 300-kilodalton cellular product correlates with E1A enhancer repression function and DNA synthesis-inducing activity.

Adenovirus E1A transforming function requires two distinct regions of the protein. Transforming activity is closely linked with the presence of a region designated conserved domain 2 and the ability of this region to bind the product of the cellular retinoblastoma tumor suppressor gene. We have investigated the biological properties of the second transforming region of E1A, which is located near the N terminus. Transformation-defective mutants containing deletions in the N terminus (deletion of residues between amino acids 2 and 36) were deficient in the ability to induce DNA synthesis and repress insulin enhancer-stimulated activity. The function of the N-terminal region correlated closely with binding of the 300-kilodalton E1A-associated protein and not with binding of the retinoblastoma protein. These results indicate that transformation by E1A is mediated by two functionally independent regions of the protein which interact with different specific cellular proteins and suggest that the 300-kilodalton E1A-associated protein plays a major role in E1A-mediated cell growth control mechanisms.     

Sugar uptake and starch biosynthesis by slices of developing maize endosperm

¹⁴C-Sugar uptake and incorporation into starch by slices of developing maize (Zea mays L.) endosperm were examined and compared with sugar uptake by maize endosperm-derived suspension cultures. Rates of sucrose, fructose, and d- and l-glucose uptake by slices were similar, whereas uptake rates for these sugars differed greatly in suspension cultures. Concentration dependence of sucrose, fructose, and d-glucose uptake was biphasic (consisting of linear plus saturable components) with suspension cultures but linear with slices. These and other differences suggest that endosperm slices are freely permeable to sugars. After diffusion into the slices, sugars were metabolized and incorporated into starch. Starch synthesis, but not sugar accumulation, was greatly reduced by 2.5 millimolar p-chloromercuribenzenesulfonic acid and 0.1 millimolar carbonyl cyanide m-chlorophenylhydrazone. Starch synthesis was dependent on kernel age and incubation temperature, but not on external pH (5 through 8). Competing sugars generally did not affect the distribution of ¹⁴C among the soluble sugars extracted from endosperm slices incubated in ¹⁴C-sugars. Competing hexoses reduced the incorporation of ¹⁴C into starch, but competing sucrose did not, suggesting that sucrose is not a necessary intermediate in starch biosynthesis. The bidirectional permeability of endosperm slices to sugars makes the characterization of sugar transport into endosperm slices impossible, however the model system is useful for experiments dealing with starch biosynthesis which occurs in the metabolically active tissue.