THE HISTOGENETIC AND BIOSYNTHETIC CAPABILITIES OF URODELE CHONDROCYTES AFTER SHORT-TERM AND PROLONGED CULTURE IN VITRO*

Urodele larval chondrocytes can be successfully maintained in long-term in vitro cultures with successive serial subculturing. In the monolayered cultures the chondrocytes actively synthesize DNA and undergo mitotic divisions, but no synthesis of mucopolysaccharide matrix takes place. The majority of the cells maintain their normal chromosome complement. Chondrocytes from short-term primary cultures, when implanted into the tail fins of host larvae, organize morphologically into typical cartilage tissue with cellular lacunae and a mucopolysaccharide matrix. When chondrocytes, which have been in monolayered cultures for long periods, are implanted as pellets into the in vivo conditions of the tail fin, they form a discrete trabecularized mass. The cells now display the capability of mucopolysaccharide matrix synthesis, but have apparently lost their histogenetic capability of forming typical cartilage tissue.     

A Comparative Study ofMiscanthus floridulus(Labill) Warb andM. transmorrisonensisHayata: Photosynthetic Gas Exchange, Leaf Characteristics and Growth in Controlled Environments

The relationship between temperature and the distribution ofMiscanthusfloridulus(Labill) Warb andM. transmorrisonensisHayata alongaltitudinal gradients in central Taiwan was examined. Responsesof biomass accumulation, leaf characteristics and photosyntheticgas exchange to growth temperature (from 10 to 30 °C) ofM.floridulusfrom an altitude of 390 m and ofM. transmorrisonensisfrom2700 m were determined. There were differences between the twospecies in above-ground biomass, CO₂uptake characteristics andleaf chlorophyll contents in response to growth temperature.The optimal temperatures for biomass accumulation were 30/25(day/night temperature) and 25/20 °C forM. floridulusandM.transmorrisonensis,respectively. Light saturated photosyntheticrates (A_max) were largest in plants grown at the optimal temperature.Growth at 15/10 and 10/10 °C compared to the optima reducedaccumulated biomass, leaf chlorophyll content and photosyntheticrate in both species with a greater reduction inM. floridulusthaninM. transmorrisonensis.We concluded that growth ofM. floridulusathigh altitude is limited by an inability to grow at temperatureslower than 15 °C, whileM. transmorrisonensisis able to growin chilling temperatures at higher altitudes.Copyright 1998Annals of Botany Company Miscanthus floridulus;M. transmorrisonensis; C₄plants; chlorophyll content; leaf growth; photosynthetic gas exchange; biomass accumulation; temperature response.