J J Parsons | PubMed Health

PubMed1988

Failure to detect changes in sarcolemma permeability in amphibian muscle following severe cellular damage.

1. Isolated amphibian hearts and pectoris cutaneous muscles were exposed either to DNP or to caffeine, thereby producing severe myofilament damage. 2. No accompanying change in sarcolemma permeability was detected by monitoring either CK or LDH release or Procion yellow entry in the heart, or by Procion entry in amphibian skeletal muscle. 3. The findings are in contrast with mammalian cardiac and skeletal muscles, and confirm that the pathways leading to myofilament degradation and to the breakdown in sarcolemma organization are separate.

Animals↗

PubMed1976

Forest to pasture: development or destruction?

The expansion of artifical or planted pastures (repasto) at the expense of both natural forest and cropland has brought major changes to the landscape and economy of Central America in recent years. On the pioneer fronts at the forest margin agriculture is commonly a transitory stage between forest felling and the establishment of permanent pasture. In the past 15 years the area in planted pasture and the total numbers of beef cattle have nearly doubled in several Central American countries while the per capita consumption of beef has actually declined. The "grassland revolution" that is occuring in Central America and Panama has been based almost exclusively on grass species of African origin which have in most cases been introduced into Central America only in this century. Of these jaragua, guinea, pangola, and kikuyu are the most important. The ecologic consequences of the conversion of forest to pasture are little understood. Intensive management practices, including the application of high-cost and scarce fertilizers and carefully-manged rotational grazing, will probably be necessary to sustain the productivity of these lands under conditions of tropical climate.

Agriculture↗