Foliar regeneration of the endangered Red Vanda,Renanthera imschootiana Rolfe (Orchidaceae)

An in vitro method was developed to regenerate large numbers of phenotypically uniform plants from the basal parts of the leaves of flowering plants of Renanthera imschootiana Rolfe. Differentiation of up to 10 shoot buds free of callus and protocorm-like bodies occurred in 10–12 weeks from the base of a single leaf implanted in Mitra et al. (1976) medium supplemented with 2% sucrose, 2 g l^-1 peptone, 44.4 M benzyladenine (BA) and 10.7 M naphthaleneacetic acid (NAA). Subculture of the tissues in medium enriched with 10% coconut water and 35 g l^-1 ripe banana pulp resulted in the production of highest average number of 40 shoots in 12 weeks. No difference in the regeneration potential was observed among the three young leaves while mature leaves did not respond. All the leaves of the regenerated shoots were easily recultured to increase shoot multiplication. Shoots readily formed roots on transfer to a medium containing 4.4 M BA, 10.7 M NAA and 1% activated charcoal. All regenerated plants examined were normal diploids with 2n=38. Foliar meristem culture appears to have great potential for ex situ conservation and propagation of this extremely endangered orchid.Abbreviations BA benzyladenine - NAA naphthaleneacetic acid     

Thermal acclimation and hardening in tadpoles of the bullfrog, Rana catesbeiana

1. 1.|Critical thermal maxima (CTMax) and minima (CTMin) were measured to evalute thermal hardening in Rana catesbeiana.

2. 2.|Tadpoles show heat hardening and CTMax acclimation, and both responses are influenced by developmental stage.

3. 3.|The first evidence of cold hardening in vertebrates is reported here.

4. 4.|Heat hardening significantly reduces cold tolerance, but there is otherwise no evidence of a cross-hardening effect.

Soybean leaf photosynthesis in relation to maturity classification and stage of growth

Leaf photosynthetic rates were measured on field-grown soybeans during the 1980 season. Comparisons were made between different cultivars and isolines representative of maturity groups I–IV. Mature, fully expanded leaves at different nodes on the plant were measured in high light to determine which had the highest potential photosynthetic rates at any one time. Successive leaves during the growing season had maximum rates which increased from about 22 mol CO₂ m^-2 s^-1 on 25 June to a peak of 30–44 mol CO₂ m^-2 s^-1 in early August.The persistency and eventual decline in the maximum rate was associated with the maturity group and related dates of flowering, pod fill and onset of senescence. Early maturing cultivars (groups I and II) had higher peak rates (38–44 mol CO₂ m^-2 s^-1) than later maturing cultivars (30–35 mol CO₂ m^-2 s^-1, groups III and IV). However, the photosynthetic rates of early maturing cultivars declined rapidly after attaining their peak, whereas the leaves of later maturing cultivars maintained their photosynthetic activity for much longer.     

Floral biology and pollinators of three co-occurring Cistus species (Gistaceae)

BOSCH, J., 1992. Floral biology and pollinators of three co-occurring Cistus species (Cistaceae). The pollination of three species of Cistus, Cistus albidus L., Cistus salvifolius L. and Cistus monspeliensis L. is studied. Insect visitors were censused and some were captured to analyse pollen distribution on their bodies. Floral phenology, breeding systems, some aspects of floral biology (pollen and nectar production, pollen-ovule ratios) and floral morphology were also studied for each species. Flowers of C. albidus produce more pollen and nectar than the other two species studied, and attract more insects, especially those with higher nutritional requirements. All three species are highly self-incompatible, but C. salvifolius and C. monspeliensis show some features that hinder xenogamy, and they have lower pollen-ovule ratios than C. albidus. As a result, this latter species apparently receives higher levels of cross-pollination, but at the cost of a higher investment to attract and reward reliable pollinators.     

Sensitive Chemiluminescence Enzyme Immunoassay for Vascular Endothelial Growth Factor/Vascular Permeability Factor in Human Serum

A sandwich chemiluminescence enzyme immunoassay for measuring the level of VEGF /VPF in serum was constructed. The detectability of the assay is very low (1.0pg/ml) and the measurable range of the assay was very wide (1–1000 pg/ml). The assay showed that the average level of VEGF /VPF in human sera from healthy blood donors was approximately 19 pg/ml.     

Flowering requirements of Scandinavian Festuca pratensis

Flowering requirements of three Scandinavian cultivars of Festuca pratensis Huds, have been studied in controlled environments. At 3 and 6°C, primary induction was independent of photoperiod, while short days (8 h) were more effective than long days (24 h) at higher temperatures. The critical temperature for induction was about 15°C in short days and about 12°C in long days. Saturation of induction required 18–20 weeks of exposure to optimal conditions. At temperatures below 12°C both induction and initiation of inflorescence primordia took place in long days, while a transition to long days was required for inflorescence initiation after primary induction in short days. A minimum of 8 long-day cycles were required for flowering of plants primary induced in short days and saturation of flowering required more than 16 cycles. The critical photoperiod for secondary induction was about 13 h. High temperature (21°C) had some devernalization effect in primary induced plants, suppressing flowering compared with 15°C.     

Experiencing winter for spring flowering: A molecular epigenetic perspective on vernalization

Many over-wintering plants, through vernalization, overcome a block to flowering and thus acquire competence to flower in the following spring after experiencing prolonged cold exposure or winter cold. The vernalization pathways in different angiosperm lineages appear to have convergently evolved to adapt to temperate climates. Molecular and epigenetic mechanisms for vernalization regulation have been well studied in the crucifer model plant Arabidopsis thaliana.Here, we review recent progresses on the vernalization pathway in Arabidopsis. In addition, we summarize current molecular and genetic understandings of vernalization regulation in temperate grasses including wheat and Brachypodium, two monocots from Pooideae, followed by a brief discussion on divergence of the vernalization pathways between Brassicaceae and Pooideae.     

Total Tocopherols,Carotenoids, and Fatty Acids Content Variation of Pistacia atlantica from Different Organs’ Crude Oils and Their Antioxidant Activity during Development Stages

The current study investigated the effect of developmental stages on the chemical composition and the antioxidant activity of fifteen crude oil samples obtained from Pistacia atlantica Desf. leaves, galls, and fruits. Twelve fatty acids were detected by GC/FID, linolenic acid (C18 : 3) was the major fatty acid detected in leaves crude oils that registered [41.73 % (P<0.05)] on the last stage. The best content of tocopherols and carotenoids was recorded at the last stage for leaves and galls oils, respectively, with values of [1.530±0.01, 0.52±0.01 (P<0.05) mg α‐tocopherol equivalent/g DW] and [86.60±0.95, 69.15±0.13 (P<0.05) μg β‐carotene equivalent/g DW]. For fruits oils, the content varied depending on the levels of fruits maturation. The results from DPPH, FRAP, and ABTS assays revealed that the antioxidant activity increased with the increasing content of tocopherols and carotenoids in leaves and galls oils during development stages, and varied for fruits oils depending on the ripening stages. Moreover, according to PCA analysis, the best phytoconstituent content and antioxidant activity were attributed to P. atlantica Desf. fruit's crude oils. Also, a strong relationship was found between the antioxidant activity and bioactive phytochemical components, such as tocopherols, carotenoids, and omega‐three fatty acid, which confirmed that P. atlantica Desf. crude oils present a valuable source of natural antioxidant that could be used for pharmaceutical and food industries purposes.