苏云金芽胞杆菌cry1A基因启动子上游区不同位点突变对BtI-lacZ融合基因表达调控的影响

利用苏云金芽胞杆菌cry1A启动子上游区的不同突变体,观测对BtI-lacZ融合基因表达的影响。结果发现,突变上游弯曲区,导致BtI-lacZ在菌株80-21中的酶活性大幅度下降,均比未突变的上游区降低2～2.5倍。而在菌株HD133-5中却出现相反的结果,即上游弯曲区的突变导致BtI-lacZ的表达比未突变体增高。如果同时突变弯曲区和反向重复区,则BtI-lacZ在菌株80-21中表达增强或下降的幅度大大减少。这表明,在cry1A启动子上游区,不同位点在转录调控上的作用不同,这种调控作用也因菌株的差异而改变。     

Apoptosis during gametogenesis in diploid and triploid turbot (Scophthalmus maximus)

Apoptosis was monitored in male and female diploid and triploid turbot encompassing a full gametogenic cycle. Results indicate that apoptosis is involved in the normal regulation of spermatogenesis progression and male germ cell fate, and provide the first evidence that the differential effects of triploidy on gonadal development include the induction of apoptosis in females.     

What loggers leave behind: Impacts on big-leaf mahogany (Swietenia macrophylla) commercial populations and potential for post-logging recovery in the Brazilian Amazon

The sustainability of current harvest practices for high-value Meliaceae can be assessed by quantifying logging intensity and projecting growth and survival by post-logging populations over anticipated intervals between harvests. From 100%-area inventories of big-leaf mahogany (Swietenia macrophylla) covering 204 ha or more at eight logged and unlogged forest sites across southern Brazilian Amazonia, we report generally higher landscape-scale densities and smaller population-level mean diameters in eastern forests compared to western forests, where most commercial stocks survive. Density of trees ≥20 cm diameter varied by two orders of magnitude and peaked at 1.17 ha⁻¹. Size class frequency distributions appeared unimodal at two high-density sites, but were essentially amodal or flat elsewhere; diameter increment patterns indicate that populations were multi- or all-aged. At two high-density sites, conventional logging removed 93–95% of commercial trees (≥45 cm diameter at the time of logging), illegally eliminated 31–47% of sub-merchantable trees, and targeted trees as small as 20 cm diameter. Projected recovery by commercial stems during 30 years after conventional logging represented 9.9–37.5% of initial densities and was highly dependent on initial logging intensity and size class frequency distributions of commercial trees. We simulated post-logging recovery over the same period at all sites according to the 2003 regulatory framework for mahogany in Brazil, which raised the minimum diameter cutting limit to 60 cm and requires retention during the first harvest of 20% of commercial-sized trees. Recovery during 30 years ranged from approximately 0 to 31% over 20% retention densities at seven of eight sites. At only one site where sub-merchantable trees dominated the population did the simulated density of harvestable stems after 30 years exceed initial commercial densities. These results indicate that 80% harvest intensity will not be sustainable over multiple cutting cycles for most populations without silvicultural interventions ensuring establishment and long-term growth of artificial regeneration to augment depleted natural stocks, including repeated tending of outplanted seedlings. Without improved harvest protocols for mahogany in Brazil as explored in this paper, future commercial supplies of this species as well as other high-value tropical timbers are endangered. Rapid changes in the timber industry and land-use in the Amazon are also significant challenges to sustainable management of mahogany.     

Economics of cage culture in Puerto Rico

Abstract

Puerto Rico has been faced with a decline of fish stocks similar to other parts of the world. Offshore cage aquaculture might be an answer to this problem although there are many unanswered questions. This paper describes a project in Puerto Rico that assessed the economics of offshore cage culture for aquaculture. The first cage was placed in the water in February 2002 with a second one to follow shortly thereafter.     

A Study of Fenpropathrin Residues in Tomatoes and Green Beans Grown in Greenhouses in Spain

The reduction in residue levels of fenpropathrin with time after treatment of tomatoes and green beans, grown in two types of commercial greenhouse in Almería, Spain, was investigated. Extracted residues were quantified by GC-ECD and their composition verified using GC-MS. Recovery of fenpropathrin from samples spiked with differing amounts of the compound were assessed. For statistical purposes, the loss of fenpropathrin with time was considered to follow a pseudo-first order reaction. The plant species and the season had a significant affect on rates of loss of fenpropathrin but the effect of the type of greenhouse and of the applied dose were not significant. © 1997 SCI.