MEXICO CITY, Nov 20 (Tierramérica) - Environmental groups say they will prevent the Mexican government from making good on its intention to release local industries from having to measure eight of the greenhouse gases they emit.

"We are protecting society from this move, which runs against transparency and the health of the population," Tania Mijares, of the Mexican Center for Environmental Law, one of the eight groups that denounced the government plans, told Tierramérica.

In September, the Environment Secretariat requested that the planned Registry of Emissions and Transference of Pollutants exclude carbon dioxide, nitrogen dioxide, sulfur hexafluoride, hydrobromofluorocarbons, hydrofluorocarbons, methane, nitrous oxide and perfluorocarbons.

The registry, which has been in the works for more than a decade and could begin operating in 2007, will be part of the reports that Mexican industries present about their emissions.

TARIJA, Nov 20 (Tierramérica) - At a conference Nov. 20-22 in the Bolivian city of Santa Cruz, experts, indigenous communities and government officials will propose public policies to protect isolated populations in South America's tropical jungles.

These communities, also known as "uncontacted", are descendants of those who resisted the inhumane exploitation of the rubber baron era in the 19th and early 20th centuries, and hid deep in the forests.

They are also survivors of the oil drilling that is going on today, as well as the extension of roads, the logging industry and the expansion of the agricultural frontier.

"The communities that live in voluntary isolation in the Amazon are the last isolated indigenous peoples existing in the world," Pablo Cingolini, of the International Work Group on Indigenous Issues, one of the conference organizers, alongside the United Nations, told Tierramérica.

Bolivia, Brazil, Colombia, Ecuador and Peru are the countries with the most isolated indigenous communities.

BUENOS AIRES, Nov 20 (Tierramérica) - Argentine researchers will present a project this month in innovations of gas heater design in order to double their efficiency and reduce their emissions of greenhouse gases.

"The heaters on the market transmit only 40 to 60 percent of the calories in the fuel," Luis Juanicó, coordinator of the project in which the National Council of Scientific Research and the National Commission of Atomic Energy are also participating, told Tierramérica.

The innovations, which will be presented Nov. 23 to executives in the business sector, consists of "introducing small fans between the cabinet and the chamber of gas, painting the chamber black, and using a cabinet that is more open and lets the heat pass," he said.

This allows 85 percent transference of heat but makes the heaters just 3.8 percent more expensive.

SAO PAULO, Nov 20 (Tierramérica) - In a pioneering initiative in Brazil, the University of Sao Paulo is studying the viability of in vitro cultivation of two threatened bivalve mollusk species in order to use some of them for producing freshwater pearls.

Larvae of the Anodontites trapesialis and Diplodon rotundus gratus will be introduced in rivers in Sao Paulo state. The two species are endangered because of water pollution, the construction of dams and the presence of invasive species.

"The production of pearls would begin in four or five years, when we complete the research and repopulation phase, and we are assured that the project doesn't hurt the environment," biologist Ricardo Cunha Lima, author of the research, told Tierramérica.

Freshwater pearls cost less, and are less shiny and darker colored than saltwater pearls.

BOGOTA, Nov 20 (Tierramérica) - Researchers at the National University of Colombia are working to raise awareness in local communities about the importance of preserving the caves where bats (Miniopterus schreibersii) seek refuge, and that bat guano is useful as organic fertilizer.

Alberto Cadena, Jimmy Ariza and Adriana Albesiano, authors of the study "Species in the arid zones of Colombia" presented this month, propose removing all of the guano from the caves and using it in farming as a replacement for chemical fertilizers.

Manuela Herrera, at the public University of the Atlantic, told Tierramérica that if the farmers take care of the caves and don't scare the bats or interfere with the flying mammal's life cycle, they will obtain significant quantities of guano, which they may also sell on the market.

The bats are important in pest control, says Herrera, because they catch as many as 600 mosquitoes per hour, and a bat colony can consume up to 125 tons per night.

TEGUCIGALPA, Nov 20 (Tierramérica) - In December the first 30 youths will graduate from a Honduran education project that for the past two years has been teaching children of farming families about environmentally friendly farming techniques.

The Virgen de Suyapa agricultural school, in El Merendón mountains, 250 km from Tegucigalpa, "is self-sustaining and teaches children under 18 about soil conservation, windbreaks and growing vegetables, as well as raising chickens and rabbits," priest Fausto Henríquez, one of the authors of the initiative, told Tierramérica.

The "servants of the environment" graduates will be "specialists in agro-ecological techniques that will allow El Merendón to continue to flourish," said Henríquez.

The range is the main environmental lung in the area of the industrial city of San Pedro Sula and holds a wealth of biodiversity.