Nickel localization on tissues of hyperaccumulator species of Phyllanthus L. (euphorbiaceae) from Ultramafic Areas of Cuba

Two species of perennial Phyllanthus (Euphorbiaceae) (Phyllanthus orbicularis and Phyllanthus discolor, both endemic to ultramafic areas of Cuba, and their natural hybrid, Phyllanthus xpallidus) were selected for metal localization microanalysis. Different plant tissues were analyzed by X-ray fluorescence, inductively coupled plasma—atomic emission spectroscopy, and scanning electron microscopy coupled with an energy-dispersive X-ray probe. All of the studied taxa are nickel (Ni) hyperaccumulators and significant concentrations of this element were found in different leaf and stem tissues. The highest Ni content was found in the laticifer tubes, whereas leaf epidermis Ni content resulted to be much more relevant in terms of total metal storage. Calcium and magnesium were found more evenly distributed in leaf and stem tissues.     

Factors affecting the abundance of introduced hedgehogs (Erinaceus europaeus) to the Hebridean island of South Uist in the absence of natural predators and implications for nesting birds

Introduced hedgehogs Erinaceus europaeus are a known threat to ground-nesting birds on many islands. Spring hedgehog density and sex ratio were measured over a 5-year period at four plots on the 315 km² Hebridean island of South Uist. The mean instantaneous density on the sandy-soiled machair plots (31.8 hedgehogs km⁻², se 2.95) was over twice that on the peaty-soiled blackland plots (15.4 hedgehogs km⁻², se 3.46), a difference reflecting the amount of preferred foraging habitat (mainly pasture). Plot population densities fluctuated approximately in unison. Year-to-year density changes were strongly correlated with temperature in the preceding winter and previous year's spring/summer, indicating that warmer conditions promote both survival and breeding success. The mean spring sex ratio of sub-adults (animals born in the previous calendar year) was not significantly different from 1M:1F. However, the 1.8M:1F ratio observed for adults was significantly male biased, probably a result of female mortality associated with rearing young. The study estimates that in an average year the South Uist hedgehog population numbers c . 2750 (95% confidence limit±800) adults and sub-adults and these produce around 3000 young. Compared with the native range, hedgehog densities on South Uist are shown to be unusually high, probably because their natural predators are absent. High hedgehog densities have led directly to high rates of egg predation of ground-nesting shorebirds and subsequent declines in bird populations. The results suggest that over the past 20 years egg losses have become more severe and control of hedgehogs more difficult because climate warming has resulted in generally more favourable conditions for hedgehogs on the islands.     

The effects of low root-zone temperature stress on two soybean (Glycine max) genotypes when combined with Bradyrhizobium strains of varying geographic origin

In areas with short growing seasons, poor early vegetative growth of soybean (Glycine max [L.] Merr.) is often attributed to the restrictive effect of cool soil conditions on nodulation and N₂-fixation by this subtropical grain legume. However, there are few studies regarding potential genetic variability of soybean and Bradyrhizobium japonicum genotypes for nodulation at cool root-zone temperatures (RZT). Experiments were conducted to (1) test for a threshold temperature for low RZT inhibition of soybean nodulation and (2) ascertain whether this threshold temperature response depends mainly on the micro- or macrosymbiont. In experiment 1 soybean seedlings (Glycine max [L.] Merr. cv. Maple Arrow) were inoculated with 1 ml of a log phase culture of B. japonicum strain 532C, H8 or H15 (the latter two strains were isolated from cold soils of Hokkaido, northern Japan) and maintained at either 16, 17.5, 19 or 25°C RZT. In experiment 2 seedlings of cv. Maple Arrow and a cold-tolerant Evans isoline were combined with strain 532C and two Hokkaido strains (H5, H30) at both 19 and 25°C RZT. Results indicated that N₂-fixation at 44 days after inoculation was substantially reduced (30–40%) by RZT as high as 19°C, due to development of less nodule mass and to a delay in the onset of N₂-fixation and a small decrease in the number of nodules formed. However, the number of nodules formed was sharply reduced and the time required for the first appearance of nodules was significantly delayed below an RZT of 17.5°C. Differences between cultivars for nodulation and N accumulation were apparent at 25°C, but were abolished by growth at 19°C, indicating that, in spite of differences in growth potential between the cultivars under optimum RZT, both cultivars were equally limited by low RZT. Differences between B. japonicum strains were consistent across temperatures and were largely attributable to higher rates of specific nodule activity recorded for strain 532C, which seemed well adapted to low RZT. These results suggest that the host plant mediates the sensitivity of N₂-fixation under low RZT and that inoculation with B. japonicum strains from cold environments is unlikely to enhance soybean N₂-fixation under cool soil conditions.     

Effect of Ocimum sanctum fixed oil on vascular permeability and leucocytes migration

Ocimum sanctum fixed oil significantly inhibited the rise in protein concentration and dye leakage in peritoneal fluid in experimentally induced peritoneal inflammation in mice. In carrageenan-induced pleurisy in rats, the fixed oil showed significant inhibition of leucocytes migration in the pleural exudate. The results suggest that the fixed oil can inhibit enhancement of the vascular/capillary permability and leucocyte migration following inflammatory stimulus.     

Leaf anatomy ofDombeya andNesogordonia (Sterculiaceae), emphasizing epidermal and internal idioblasts

We studied leaf anatomy, using clearings, resin sections, and scanning electron microscopy, from mostly herbarium specimens of 123 species ofDombeya and 11 species ofNesogordonia (Sterculiaceae). Species were placed in seven idioblast categories, ranging from those without any to single and bicelled epidermal forms to multicelled nodules and single mesophyll idioblasts. Idioblast contents are possibly mucilaginous, but were not identified. In these two genera the range of foliar idioblast morphology surpasses that known previously for the entire family. Leaves are dorsiventral with mostly abaxial anomocytic stomata and typical palisade and spongy layers; paraveinal mesophyll is lacking. Miniature glandular (clavates, capitates) and nonglandular (mostly stellate) trichomes occur. Prismatic crystals predominate; epidermal prismatics and mesophyll druses are rare.     

Embryonic and larval development of brown trout, Salmo trutta L.: exposure to trace metal mixtures in soft water

Freshly fertilized ova of brown trout, Salmo trutta L., were exposed to all possible mixtures of Al (6000 nmol 1¹), Cu (80 nmol 1⁻¹), Pb (50 nmol 1⁻¹) and Zn (300 nmol 1 ¹). In a separate experiment, newly hatched brown trout yolk-sac fry were exposed to Mn (1500 nmol 1⁻¹), Fe (2500 nmol 1 ¹), Ni (200 nmol 1⁻¹) or Cd (4 nmol 1 ¹), separately, and in mixtures with either Al or Cu. Both experiments were conducted in flowing, artificial softwater media nominally at pH 5.6 [Ca] 20 μmol 1 ¹ and 10° C.
Mortalities were high in fry subjected to treatments which contained both Al and Cu (31–72%), and to the Cu + Fe treatment (78%) compared with those from the other trace metal mixtures (0–22%). In all the treatments tested, fry exposed to trace metal mixtures containing Al and/or Cu had reduced whole body Ca, Na and K content, and seriously impaired skeletal calcification. Whole body Mg content was variable. In trace metal mixtures which contained Cu but not Al, the effects on fry survival and whole body mineral content were in general more deleterious than the corresponding mixtures but with Al present rather than Cu. The presence of Pb and/or Zn in mixtures with Al and/or Cu had a slight ameliorative effect in terms both of fry survival and whole body mineral content.     

Plant growth-promoting rhizobacteria do not pose any deleterious effect on cowpea and detectable amounts of ethylene are produced

Summary The use of trap crops such as cowpea could reduce the effects of the root parasitic weed, Striga hermonthica and its subsequent constraints on the growth of cereals. Certain bacteria could augment the trap crop stimulatory effect. We studied the effect of three bacteria introduced to the rhizosphere of three cowpea varieties at planting. Number of days to cowpea flowering was noted and at harvest, data were collected on pod characteristics and biomass. Means of data subjected to ANOVA were compared using Tukey’s Studentized Range Test. We analysed bacterial headspace volatiles for ethylene by gas chromatography and gas chromatography–mass spectrometry. Bacterial type significantly influenced the cowpea varieties with better performance over the non-inoculated control. Average pod weight (g) with bacterial treatment was 37.97 for Enterobacter sakazakii 8MR5, 34.38 for Pseudomonas 44MS8 and 27.46 for Pseudomonas 10M3. Non-inoculated control had an average weight of 20.98 g. Bacteria promoted a significant increase in pod weight (≥30.89%), fresh biomass (≥24.22%), and improved pod number (≥20.54%) and pod wall thickness (≥7.33%) with no deleterious effect on plant health. Ethylene released by the bacteria ranged from trace concentrations in Pseudomonas sp. to 210 nmoles/10⁸ c. f. u./ml in Ent. sakazakii 8MR5.     

High-frequency plant regeneration by <Emphasis Type="Italic">in vitro</Emphasis> shoot proliferation in cotyledonary node explants of grasspea (<Emphasis Type="Italic">Lathyrus sativus</Emphasis> L.)

Summary Multiple shoots were induced from cotyledonary nodes of grasspea (Lathyrus sativus L.) derived from 7-d-old in vitro seedlings on Murashige and Skoog (MS) medium containing N⁶-benzyladenine (BA), kinetin, or thidiazuron, BA being the most effective. Among the five genotypes tested, shoot proliferation frequency was the highest (93.3%) for IC-120487, giving the maximum number of shoots (11.3 shoots per explant) on MS medium augmented with 2.0 mgl⁻¹ (8.87 μM) BA. Shoot cultures were established by repeatedly subculturing the original cotyledonary nodes on fresh medium after each harvest of the newly formed shoots. Thus 30–40 shoots were obtained in 2 mo. from a single cotyledonary node. Up to 81.8% of the shoots developed roots following transfer to half-strength MS medium containing 0.5 mgl⁻¹ (2.85 μM) indole-3-acetic acid. Plantlets were successfully acclimatized and established in soil.