Olfactory memory: the long and short of it

It has been proposed that memory for odors does not have a short-term (or working) memory system. The distinction between short- and long- term memory in other sensory modalities has been generally supported by three main lines of evidence: capacity differences between the proposed systems, evidence of differential coding, and differential memory losses in neuropsychological patients. The present paper examines these issues in an effort to establish a similar distinction for the memory of olfactory stimuli. Each of these lines of evidence is examined in relation to the literature on olfactory memory. Based on this examination, it seems that there is at least preliminary support from each of these lines of evidence to advocate a distinction between a long- and short-term memory for olfactory stimuli. Emphasis is placed upon the qualitative similarity of olfactory memory to other memory systems. This similarity is further highlighted through an examination of the literature pertinent to serial position effects in memory for olfactory stimuli.      

Interpretation of soil δ13C as an indicator of vegetation change in African savannas

Question: The relationship between carbon‐13 in soil organic matter and C₃ and C₄ plant abundance is complicated because of differential productivity, litter fall and decomposition. As a result, applying a mass balance equation to δ¹³C data from soils cannot be used to infer past C₃ and C₄ plant abundance; only the proportion of carbon derived from C₃ and C₄ plants can be estimated. In this paper, we compare δ¹³C of surface soil samples with vegetation data, in order to establish whether the ratio of C₃:C₄ plants (rather than the proportion of carbon from C₃ and C₄ plants) can be inferred from soil δ¹³C. Location: The Tsavo National Park, in southeastern Kenya. Methods: We compare vegetation data with δ¹³C of organic matter in surface soil samples and derive regression equations relating the δ¹³C of soil organic matter to C₃:C₄ plant abundance. We use these equations to interpret δ¹³C data from soil profiles in terms of changes in inferred C₃:C₄ plant ratio. We compare our method of interpretation with that derived from a mass balance approach. Results: There was a statistically significant, linear relationship between the δ¹³C of organic matter in surface soil samples and the natural logarithm of the ratio of C₃:C₄ plants in the 100m² surrounding the soil sample. Conclusions: We suggest that interpretation of δ¹³C data from organic matter in soil profiles can be improved by comparing vegetation surveys with δ¹³C of organic matter in surface soil samples. Our results suggest that past C₃ plant abundance might be under‐estimated if a mass balance approach is used.     

Extra DNA in the T region of crown gall Ti-plasmid pTiA66

The mutant tumorigenic phenotype of pTiA66, a derivative of the broad host range octopine Ti-plasmid pTiA6, results from a 2.6-Kb insertion into EcoRI fragment 32g of the T region, which has been implicated in the auxin synthesis disruption tumor character. The inserted DNA is closely related to sequences from BamHI fragment 11 of the same or a related plasmid but probably originally derives from a chromosomal sequence.     

Isolation,characterization, and genetic analysis ofAspergillus nidulans mutants resistant to the antifungal compound LY214352

We have isolated and characterized six chemically induced mutants of the filamentous fungusAspergillus nidulans that are resistant to the experimental fungicide 8-chloro-4-(2-chloro-4-fluoro-phenoxy)quinoline (LY214352). The mutants are 13- to 430-fold more resistant to LY214352 than the parental strain, and one of the mutant strains requires LY214352 for maximal growth. The resistance trait is governed by a single dominant or partially dominant gene in each mutant, and it is likely that all of the mutations are allelic. The LY214352-resistant mutants were not cross-resistant to other compounds that inhibit the growth ofA. nidulans. The implications of these findings on the potential for development of resistance to LY214352 are discussed.