Glycinebetaine content of halophytes: Improved analysis by liquid chromatography and interpretations of results

The glycinebetaine content of plants can be determined by simple isocratic high performance liquid chromatography. The method is applicable to extracts from a wide range of species and, in most cases, is suitably rapid and specific to be preferable to other methods of analysis. The chromatographic system employed permits accurate and sensitive ultraviolet detection, free of most interferences. Because the principle plant carbohydrates elute well before glycine betaine, preparative ion exchange procedures can be simplified. Twenty-seven species, mostly inland halophytes, were screened by these methods and 13 were found to be glycinebetaine accumulators. On a dry weight basis, the glycinebetaine content of Salicornia europaea L. actually declined with exposure to progressively higher levels of NaCl. When expressed as a proportion of plant organic matter, however, patterns were more typical (up to 7.7% at higher salt concentrations).     

Assessment of temporal changes in haem and protein levels in Ixodid ticks following blood engorgement, and their use as age-grading parameters

Nymphs of Rhipicephalus appendiculatus and Hyalomma anatolicum anatolicum were fed on rabbits and maintained in the laboratory to allow moulting and further development. At specified time intervals from 0 to 500 days after engorgement, samples of ticks were ground individually in distilled water within the wells of an agglutination plate. A 0.1 ml aliquot was removed from each and levels of haemin and protein assessed from optical density values at specific wavelengths in a spectrophotometer.

Both protein and haemin levels showed an initial rapid decrease after engorgement; values did not fall to zero in either case but showed marked fluctuation throughout the study period. These fluctuations combined with the high standard errors of the results, made assessments of the physiological age of individual ticks impossible.

Such fluctuating values, however, suggested the possibility that haem biosynthesis might be taking place, and this was tested by injecting the radioactively-labelled haem precursor [4-¹⁴C]δ-amino laevulinic acid into engorged nymphs, immediately following their detachment. Both tick species revealed an incorporation of this compound into their haematin content, although neither incorporated the non-haem precursor [1-¹⁴C]2-amino isobutyric acid. These results indicate an ability of ticks to synthesize haem in vivo, although the underlying reasons for such a mechanism remain unknown.     

Correlation of pulmonary ACE activity and capillary surface area during postnatal development

Although a considerable amount of information is available regarding the remodeling and growth of the pulmonary arterial circulation, relatively little is known regarding postnatal development of the pulmonary microcirculation. We hypothesized that the maximal velocity (Vmax) of pulmonary angiotensin-converting enzyme (ACE) activity, measured from indicator-dilution outflow curves using a synthetic substrate, 3H-labeled benzoyl-phenylalanyl-alanyl-proline (BPAP), is directly related to the capillary endothelial cell surface area in the lungs of developing lambs. Accordingly we measured apparent kinetics of pulmonary ACE activity in 22 anesthetized ventilated lambs (2-171 days old) and compared our functional assessment to simultaneous in vivo determinations of CO diffusing capacity (DLCO) and postmortem structural assessment of alveolar septal dimensions using stereology and electron microscopy. There was a progressive increase in Vmax of ACE in this age group, with little change in apparent affinity for BPAP. Similar functional manifestation of growth was noted by an age-dependent increase in DLCO. Neither Vmax nor DLCO was significantly affected by an increase in left atrial pressure to 19 Torr (via inflation of a balloon in the left atrium), suggesting little recruitment of vessels under conditions of the present protocol. A close correlation was observed when either Vmax for ACE activity or DLCO was plotted vs. capillary endothelial cell surface area. Double logarithmic transformation of capillary endothelial cell surface area, Vmax-ACE and DLCO vs. lung volume revealed power functions with slopes all greater than that predicted from isotropic growth, suggesting selective differential postnatal development of the endothelium of the alveolar septum in lambs from 2-171 days of age.     

The effect of drought on levels of abscisic acid,cytokinins, gibberellins and ethylene in aeroponically-grown sunflower plants

Abscisic acid (ABA), cytokinins and gibberellin-like substances (GAs) were extracted from the roots and shoots of 17-day-old sunflower seedlings which had been droughted or were unstressed. Plants were grown in an aeroponic chamber which allowed for good control over degree of water stress and easy access to roots. Following methanolic extraction of lyophilized material, cytokinins were separated from the acidic growth-regulators on a cellulose PO₄ cationic exchange column. The cytokinins were analysed by paper chromatography and HPLC and the soybean hypocotyl section assay. Semipurified acidic regulators were chromatographed on SiO₂ columns and HPLC and aliquots assayed with the dwarf rice cv. Tan-ginbozu bioassay for GAs. Fractions known to contain ABA were purified by sequential reverse-phase HPLC of the acid and then of the methyl ester forms followed by quantitation as Me-ABA on GLC-EC. ABA losses were measured by using an internal standard [³H]-ABA). Ethylene production was also monitored in stressed and unstressed seedlings.The effect of drought on GAs and ethylene was minimal. The ABA levels were markedly higher in droughted plants. Stressed roots had 32 times more ABA than controls. The levels of cytokinins in the shoots of droughted plants were about half those in unstressed shoots, and qualitative differences occurred in the roots. Under stress a large peak of activity was present similar to zeatin glucoside which was not present in the unstressed condition. The results are discussed in relation to drought-effects on metabolism.     

Binding of inositol trisphosphate by a liver microsomal fraction.

To test the hypothesis that inositol trisphosphate (InsP3) mediates adaptation and excitation in invertebrate photoreceptors, we measured its formation on a rapid time scale in squid retinas. For squid, excitation and adaption occurs within 0.1 and 1-2 s respectively. We could detect an elevation in InsP3 within 200 ms of a bright flash. This increase is about 240% over dark basal levels and is maintained for at least 2 min after a flash. The increase probably occurs in the photoreceptors, which are the only neurons in squid retinas. Analysis by h.p.l.c. indicates that the light-regulated isomer is Ins(1,4,5)P3, which is formed by the hydrolysis of phosphatidylinositol bisphosphate (PtdInsP2).     

Regulation of insulin mRNA abundance and adenylation: dependence on hormones and matrix substrata.

The insulin mRNA levels of rat insulinoma cell lines increased six- to eightfold, and the cells entered a transient state of growth arrest when they were cultured in serum-free, hormonally defined medium and on an extract of extracellular matrix derived from a basement membrane-secreting tumor line, EHS. Insulinoma cultures in growth arrest responded to glucose with a two- to threefold increase in insulin secretion associated with an insulin mRNA that contained a poly(A) tail that was 120 to 140 bases longer than normal.     

Interaction of neuroleptic drugs with a synthetic calcium-binding peptide analog of site III of rabbit skeletal troponin C. Phenothiazine selective binding

The effects of nine drugs on the CD spectra of a synthetic calcium binding analog of site III of rabbit skeletal troponin C, can generally be divided into 3 groups: (1) that consisting of haloperidol, benperidol, molindone and promethazine, had no effect on the CD spectrum or calcium sensitivity of the apopeptide; (2) that composed of structurally rigid thioxanthenes, induced CD-detectable structural change in the apopeptide but prevented Ca2+-induced structural change; (3) that consisting of chlorpromazine, trifluoperazine and fluphenazine, induced structural change in the peptide but had no effect on the Ca2+-induced structural change.     

Effects of Nitrogen Sources on Cellulose and Synthetic Lignin Degradation by Phanerochaete chrysosporium

Phanerochaete chrysosporium degraded cellulose faster with organic nitrogen sources than with NH₄Cl. Simple and complex nitrogen sources added at the time of inoculation to N-limited cultures of P. chrysosporium, with glucose as carbon/energy source, transiently stimulated degradation of synthetic [¹⁴C]lignin to ¹⁴CO₂. The same nitrogen sources added 5 days after inoculation, when the cultures were entering secondary metabolism, delayed ¹⁴CO₂ production. The various N sources affected synthetic lignin degradation in defined medium differently than lignin degradation in aspen wood.     

Confirmation of Occurrence of Hydroxamate Siderophores in Soil by a Novel Escherichia coli Bioassay

The occurrence of ferrichrome-type hydroxamate siderophores in soil was confirmed. In the presence of the iron-scavenging chelator ethylenediamine[di(o-hydroxyphenylacetic)acid], soil extract stimulated the growth of an Escherichia coli strain possessing the ferrichrome transport protein (TonA) but did not stimulate growth of a strain lacking this protein (TonA⁻). The siderophore concentration in a 1:1 (soil-water) extract was estimated to be approximately 78 nM. Specificity of the assay was supported by the absence of significant differential strain responses to ferric citrate, ferric 2,3-dihydroxybenzoate, enterochelin, ferrioxamine B, coprogen, and triacetylfusigen.