The effects of the herbicide tebuthiuron on seedlings of Mimosa pigra and native floodplain vegetation in northern Australia

Abstract We studied the seedbank of floodplain vegetation in three major tropical river systems in northern Australia, which had been variously invaded by the tropical woody weed Mimosa pigra. The sites selected had not previously been treated with tebuthiuron, a herbicide which is widely used in northern Australia to control Mimosa. We collected soil seedbank samples from two floodplain vegetation types (Melaleuca swamp and sedgeland), and, within each type, from areas in which Mimosa was either present or absent. The effects of treatment with tebuthiuron at 15 kg ha^?1, twice the usual recommended rate, was subsequently assessed in die laboratory on the soil-seedbank samples. Ordination of the species composition of seedlings which emerged from the soil seedbank samples showed no effect of (i) the vegetation community from which the samples were collected, (ii) the presence of adult Mimosa, or (iii) treatment with tebuthiuron. The effect of tebuthiuron on the emergence and mortality of seedlings from four functional groups (grasses, sedges, forbs and Mimosa) was also tested on the seed bank samples. Emergence was significantly decreased by tebuthiuron only for forbs from Melaleuca swamps. The mortality of Mimosa was significantly higher than that of the other functional groups, but there was some mortality of forb and grass seedlings. Sedges, however, were unaffected. The impact of tebuthiuron on Mimosa depended on soil clay content—in the soils with lowest clay content, tebuthiuron was the most effective in killing Mimosa seedlings. Mortality in forb and grass seedlings, in contrast, was not affected by soil clay content. Tebuthiuron was therefore selective against Mimosa seedlings. However, even at twice the recommended rate of application for killing adult Mimosa, under ideal conditions for distribution of the herbicide through the soil, 43% of Mimosa seedlings survived. Given the size of the Mimosa seedbank under field conditions (～10 000 seeds/m²), tebuthiuron can therefore not be considered an effective herbicide against Mimosa seedlings.     

Comparative Analysis of Melanins and Melanosomes Produced by Various Coat Color Mutants

Pigmentation in the skin, hair, and eyes of animals is influenced by a number of genes that modulate the activity of melanocytes, the intervention of enzymatic controls at different stages of the melanogenic process, and the physico-chemical properties of the final pigment. The results of combined phenotypic, ultrastructural, biochemical, and chemical analyses of hairs of a variety of defined genotypes on a common genetic background performed in this study are consistent with the view that pigmentation of dark to black hairs results from the incorporation of eumelanin pigments whereas that of yellow hairs results from the incorporation of eu- and pheomelanins. It is also clear that relatively minor differences in melanin content can have dramatic effects on visible hair color. A good correlation was found for expression of (and enzyme activities associated with) TRP1 and TRP2 with eumelanin synthesis and eumelanosome production.     

FOUNDING A NEW SCIENCE: MIND GENOMICS

We present in this article our vision for a new science, modeled on the emerging science of genomics and the technology of informatics. Our goal in this new science is to better understand how people react to ideas in a formal and structured way, using the principles of stimulus–response (from experimental psychology), conjoint analysis (from consumer research and statistics), Internet‐based testing (from marketing research) and multiple tests to identify patterns of mind‐sets (patterned after genomics). We show how this formal approach can then be used to construct new, innovative ideas in business. We demonstrate the approach using the development of new ideas for an electronic color palette for cosmetic products to be used by consumers.     

Synapse Regeneration, Axon Sprouting and Degeneration in the Central Nervous System of the Leech

SYNOPSIS. Detailed know ledge of the projections and synapticconnections of identifiable neurons in the leech has permitteda similarly detailed study of the sprouting, regeneration, anddegeneration of axons We have learned that certain cellularcomponents, such as synaptic targets and gha, may play onlya limned role in synapse regeneration and in axon degenerationYet contact with the synaptic target may inhibit sprouting andavailability of targets may promote it Overall, results in theleech support the idea that degeneration as well as regenerationshare fundamental mechanisms with other invertebrates and thevertebrates including mammals.     

The volatile organic compounds of introduced and native dung and carrion and their role in dung beetle foraging behaviour

1. The decomposition of biological material produces a plethora of volatile organic compounds (VOCs), which are implicated in the foraging behaviour of coprophagous and necrophagous insects. Dung beetles (Coleoptera: Scarabaeidae: Scarabaeinae) have an acute olfactory system used to locate food resources. Accordingly, identification of food resource VOCs potentially used in food location is integral to understanding dung beetle foraging ecology. 2. In this study, volatile emissions from dung and carrion of native and introduced animals in New Zealand were analysed using solid‐phase microextraction (SPME) and gas chromatography‐mass spectrometry (GC‐MS). Volatile profiles were compared via principal component analyses (PCAs) and cluster solutions based on attractiveness using canonical discriminant analysis (CDA). 3. A total of 115 compounds were detected from 21 food types. Statistical analyses showed that dung and carrion volatile profiles clustered according to attractiveness to the dung beetle Saphobius edwardsi, and that different dung types formed distinct clusters and grouped separately from carrion. 4. This study suggests that volatile profiles emitted by food resources used by dung beetles are complex, producing distinct odours, which potentially mediate foraging decisions.     

Sucrose Breakdown in Relation to Fruit Growth of Acid Lime (Citrus aurantifolia)

The physiological capacity for sucrose breakdown in developingjuice sac cells of acid limes was estimated by assaying theactivity of the three enzymes of sucrose catabolism in additionto vacuolar acid hydrolysis. The maximum potential rates ofsucrose breakdown were compared with the observed rates of carbonutilization. Highest potential rates of sucrose breakdown (28.621mmol cm^–3 per hydrated active space d^–1) occurredat the initial stages of fruit development where carbon utilizationwas highest. As the fruit developed, the potential rates ofsucrose breakdown and carbon utilization declined to very lowlevels. At 80% of development, vacuolar acid hydrolysis becamethe only physiological mechanism for sucrose breakdown. Therelatively low amounts of sucrose hydrolysed by acid hydrolysisat this time were just sufficient to account for the measuredcarbon demands. The results suggest that carbon supplied bythis distinct sucrose catabolizing system is able to provideadequate levels of carbon skeletons for the observed levelsof respiration and dry weight deposition early in development,but becomes a limiting factor for growth in the later stages. Key words: Vacuolar acid hydrolysis, Citrus aurantifolia     

Permethrin resistance in the head louse Pediculus capitis from Israel

Head lice, Pediculus capitis , were collected from children aged 3–12 years in Maale Adumin, a town near Jerusalem, after reports of control failure with the pyrethroid insecticide permethrin. A total of 1516 children were examined: living lice and eggs were found on 12.1% of the children; or another 22.8% of the children only nits were found. Twice as many girls as boys (8.1% v 4%) were infested with lice and or nits. Head lice collected from infested children were exposed to permethrin impregnated filter-papers. Log time probit mortality (ltp) regression lines were calculated for mortality data and compared to ltp lines for a similar collection of head lice made in 1989. The regression lines for the two years were significantly different, with a 4-fold decrease in susceptibility at the LT50 level between 1989 and 1994. The slopes of the lines also suggested that the 1994 population was more heterogenous in its response to permethrin than the 1989 population. In contrast, a laboratory population of body lice (Pediculus humanus) tested with the same batch of permethrin-impregnated papers showed a slight but non-significant increase in susceptibility between 1989 and 1994. The results suggest that resistance to pyrethroids has developed rapidly among head lice since permethrin was introduced in 1991 as a pediculicide in Israel.     

Preferential Marriage among the Rukuba of Benue-Plateau State, Nigeria

The overall system of Rukuba marriage is formally a straight exchange of women between the component units of two exogamous moieties, component units which in turn abduct each other's wives in secondary marriage. The youths and girls of each of these component units pair off in formalized premarital relationships until girls marry out in the other moiety. The exchange pattern between the moieties works in such a way that the eldest girl of a set of uterine sisters must marry her mother's last lover's son, and her junior sisters are preferentially married in their mother's natal component unit, thus introducing a delayed exchange between the component units of opposite moieties working concurrently with the straight exchange system between the moieties. This is made possible by the various combinations of primary and/or preferential marriage and subsequent secondary marriages. [Rukuba, moieties, Nigeria, preferential marriage]     

Identification and characterization of simple sequence repeat (SSR) markers derived in silico from Brassica oleracea genome shotgun sequences

The availability of sequence data derived from shotgun sequencing programs enables mining for simple sequence repeats (SSRs), providing useful genetic markers for crop improvement. This study presents the development and characterization of 40 SSR markers from Brassica oleracea shotgun sequence and their cross‐amplification across Brassica species. The markers show reliable amplification, genome specificity and considerable polymorphism, demonstrating the utility of SSRs for genetic analysis of commercial Brassica germplasm.