Intraspecific variation in Licuala glabra Griff. (Palmae) in Peninsular Malaysia– a morphometric analysis

We studied vegetative and reproductive characters of 74 herbarium specimens of Licuala glabra Griff. (Palmae) collected from 22 localities throughout Peninsular Malaysia. To test the null hypothesis that there are no distinct groups within the species, cluster analysis (nearest neighbour), principal coordinates and principal components analyses were performed on the set of 43 qualitative and quantitative characters. The results obtained suggested that: (1) there are three infraspeciflc groups within the species, viz., the two published varieties glabra and selangorensis as well as a possible third novel taxon; (2) there is clustering of individuals corresponding to their geographic localities; (3) clusters generated using only reproductive characters indicate a biogeographic distribution of populations correlated with the mountain ranges in the peninsula.     

Population Analysis of Licuala glabra Griff. var. glabra (Palmae) using RAPD Profiling

Random amplified polymorphic DNA (RAPD) profiling revealed geneticdiversity among three populations ofLicuala glabra var. glabra,an understorey palm growing in the dipterocarp forests of Terengganu,Malaysia. The Bukit Bauk population had individuals withoutaerial stems. The Bukit Besi individuals had stem heights to30 cm, while those of the Rasau Kerteh population had stemsup to 4 m in height. Southern blot analysis confirmed that anapparent monomorphic band generated by the primer OPU-17 amongthe three different populations corresponds to the same locus.Six primers were used to generate 87 RAPD bands that formed2-state character raw data for estimating genetic distancesusing the simple matching coefficient of similarity. The phenogramgenerated by UPGMA of the RAPD data grouped the individualsfrom the three populations under three clusters. This was inagreement with the morphological grouping. The infraspecificL. glabra var.selangorensis Becc. was grouped closer to theL. glabra var. glabra individuals than to the outgroupL. scortechiniiBecc. Principal component analysis supported the observationfrom the phenogram. The results show discrete genetic structuringin the populations studied and provide useful information forfuture conservation measures. Copyright 1999 Annals of BotanyCompany Licuala glabra Griff. var. glabra, RAPD, palm, AMOVA, population, genetic diversity, conservation.     

Tillering, Leaf Expansion and Growth of Plants of Two Cultivars of Perennial Ryegrass Grown using Hydroponics at Two Water Potentials

Tillering and growth parameters of perennial ryegrass cultivarsWendy (diploid) and Condesa (tetraploid) were determined ina glasshouse experiment using hydroponics at low (–1·3MPa) and normal water potential (0 MPa). At –1·3MPa, leaf extension rate was reduced by 36%. Final plant tillernumber was 20% lower at –1·3 MPa because of a 12%reduction in the leaf appearance rate in the first weeks afterthe start of the treatments. Site filling, the relative increasein tiller number per leaf appearance interval, was high (0.61)-butstill lower than theoretically possible-and was only slightlyaffected by water potential. Site filling was shown to be strictlyrelated to the number of inhibited plus unemerged tiller buds.Dry matter production was 64% lower at –1·3 MPa.Relative growth rate (RGR) was, on average, 17% lower at –1·3MPa, but the reduction was greater just after the treatmentsstarted. Also, net assimilation rate (NAR) was reduced moreby low water potential just after the start of the treatments.Specific leaf area (SLA) was 13 % lower at –1·3MPa for Wendy, but not significantly reduced for Condesa. Contraryto expectations based on the theory of the functional balancebetween root and shoot, leaf weight ratio was slightly higherat –1·3 MPa. From comparison of the results ofthis study with published data, it is concluded that effectsof drought in the field on tillering cannot be attributed onlyto low water potential. Lolium perenne L., perennial ryegrass, tillering, site filling, leaf appearance, leaf extension, growth analysis, water potential     

A diastolic dysfunction model in non-human primates with transverse aortic constriction

Transverse aortic constriction (TAC) has been widely used to study cardiac hypertrophy, fibrosis, diastolic dysfunction, and heart failure in rodents. Few studies have been reported in preclinical animal models. The similar physiology and anatomy between non-human primates (NHPs) and humans make NHPs valuable models for disease modeling and testing of drugs and devices. In the current study, we aimed to establish a TAC model in NHPs and characterize the structural and functional profiles of the heart after TAC. A non-absorbable suture was placed around the aorta between the brachiocephalic artery and left common carotid artery to create TAC. NHPs were divided into 2 groups according to pressure gradient (PG): the Mild Group (PG=31.01 ± 12.40 mmHg, n=3) and the Moderate Group (PG=53.00 ± 9.37 mmHg, n=4). At 4 weeks after TAC, animals in both TAC groups developed cardiac hypertrophy: enlarged myocytes and increased wall thickness of the left ventricular (LV) anterior wall. Although both TAC groups had normal systolic function that was similar to a Sham Group, the Moderate Group showed diastolic dysfunction that was associated with more severe cardiac fibrosis, as evidenced by a reduced A wave velocity, large E wave velocity/A wave velocity ratio, and short isovolumic relaxation time corrected by heart rate. Furthermore, no LV arrhythmia was observed in either animal group after TAC. A diastolic dysfunction model with cardiac hypertrophy and fibrosis was successfully developed in NHPs.     

Density‐mediated indirect interactions alter host foraging behaviour of parasitoids without altering foraging efficiency

1. Foraging decisions of parasitoids are influenced by host density via density‐mediated indirect interactions. However, in the parasitoid's environment, non‐suitable herbivores are also present. These non‐hosts also occur in different densities, which can affect a parasitoid's foraging behaviour. 2. The influence of non‐host densities can be expressed during the first phase of the foraging process, when parasitoids use plant volatiles to locate plants infested by their host. They may also play a role during the second phase, when parasitoids use infochemicals from the host and plant to locate, recognise and accept the host. 3. By using laboratory and field setups, it was studied whether the density of non‐host herbivores influences these two phases of the foraging behaviour of the parasitoid Cotesia glomerata as well as the parasitoid's efficiency to find its host, Pieris brassicae caterpillars. 4. The findings show that a high non‐host density, regardless of the species used, negatively affected parasitoid preference for host‐infested plants, but that the behaviour on the plant and the total host‐finding efficiency of the parasitoids were not influenced by non‐host density. 5. These results are discussed in the context of density‐mediated indirect interactions.