Biophysical characteristics of successful oilseed embryo cryoprotection and cryopreservation using vacuum infiltration vitrification: an innovation in plant cell preservation.

Heterogeneity in morphology, physiology and cellular chemistry of plant tissues can compromise successful cryoprotection and cryopreservation. Cryoprotection is a function of exposure time × temperature × permeability for the chosen protectant and diffusion pathway length, as determined by specimen geometry, to provide sufficient dehydration whilst avoiding excessive chemical toxicity. We have developed an innovative method of vacuum infiltration vitrification (VIV) at 381 mm (15 in) Hg (50 kPa) that ensures the rapid (5 min), uniform permeation of Plant Vitrification Solution 2 (PVS2) cryoprotectant into plant embryos and their successful cryopreservation, as judged by regrowth in vitro. This method was validated on zygotic embryos/embryonic axes of three species (Carica papaya, Passiflora edulis and Laurus nobilis) up to 1.6 mg dry mass and 5.6 mm in length, with varying physiology (desiccation tolerances) and 80 °C variation in lipid thermal profiles, i.e., visco-elasticity properties, as determined by differential scanning calorimetry. Comparisons between the melting features of cryoprotected embryos and embryo regrowth indicated an optimal internal PVS2 concentration of about 60% of full strength. The physiological vigour of surviving embryos was directly related to the proportion of survivors. Compared with conventional vitrification, VIV-cryopreservation offered a ∼ 10-fold reduction in PVS2 exposure times, higher embryo viability and regrowth and greater effectiveness at two pre-treatment temperatures (0 °C and 25 °C). VIV-cryopreservation may form the basis of a generic, high throughput technology for the ex situ conservation of plant genetic resources, aiding food security and protection of species from diverse habitats and at risk of extinction.

Evaluation of wound healing activity of Allamanda cathartica. L. and Laurus nobilis. L. extracts on rats

BACKGROUND: Allamanda cathartica. L. is a perennial shrub used in traditional medicine for treating malaria and jaundice. Laurus nobilis. L. is a tree and has been used for its astringent, healing and diuretic properties. The objective of this study was to investigate the aqueous extracts of Allamanda and Laurus nobilis to evaluate their wound healing activity in rats.METHODS: Excision and incision wound models were used to evaluate the wound healing activity of both the extracts on Sprague Dawley rats. In each model, animals were divided into four groups of 10 animals each. In both the model, group 1 served as control and group 2 as reference standard. In an excision wound model, group 3 animals were treated with Allamanda (150 mg kg-1 day-1) and group 4 animals were treated with Laurus nobilis (200mg kg-1 b.w day-1) for 14 days respectively. In the case of incision wound model, group 3 and 4 animals were treated with the extracts of Allamanda and Laurus respectively for 10 days. The effects of vehicles on the rate of wound healing were assessed by the rate of wound closure, period of epithelialisation, tensile strength, weights of the granulation tissue, hydroxyproline content and histopathology of the granulation tissue.RESULTS: The aqueous extract of Allamanda promoted wound healing activity significantly in both the wound models studied. High rate of wound contraction (P < .001), decrease in the period of epithelialisation (10.2 ñ0.13), high skin breaking strength (440.0 ñ 4.53), significant increase in the weight of the granulation tissue (P <.001) and hydroxyproline (P < .001) content were observed in animals treated with the aqueous extract of Allamanda. Histological studies of the granulation tissue from the Allamanda treated group showed the presenceof a lesser number of inflammatory cells, and increased collagen formation than the control.

In Laurus nobilis treated animals, the rate of wound contraction, weight of the granulation tissue and hydroxyproline content were moderately high (P < .05). The histological study of the granulation tissue of the Laurus nobilis treated animals showed larger number of inflammatory cells, and lesser collagen when compared with the Allamanda treated group of animals. However, it was better than the control group of animals.CONCLUSION: The data of this study indicated that the leaf extract of Allamanda possesses better wound healing activity than the Laurus nobilis and it can be used to treat different types of wounds in human beings too.