Genetic variation in the Epacris tasmanica complex (Epacridaceae).

RAPD (random amplified polymorphic DNA) markers were used to delimit species in the Epacris tasmanica complex (Epacridaceae) collected from various locations in Tasmania, Australia. The RAPD analysis placed morphologically similar taxa located closely geographically into discrete clusters. However, geographically distant populations of morphometrically similar taxa, such as the southern and northern Tasmanian populations of E. virgata and E. tasmanica, were less closely related to each other than those taxa classified as different species. The most geographically remote population (E. glabella [Serpentine Hill]) shared the least genetic similarities with the other taxa. The genetic information obtained from this study reinforces some previous morphometric data used to delimit species in the E. tasmanica complex. Furthermore, the strong geographical structure of the genetic variation is consistent with a model in which gene flow between populations is limited

An ultrastructural and functional assessment of nasal cilia and spermatozoa in an infertile human male and healthy controls

Ciliary disorders are complex and enigmatic, and can lead to and complications. Human males who produce spermatozoa with defective flagella may also possess defective cilia. In this the motility and ultrastructure ofnasal cilia/cells and spermatozoa of an infertile Tasmanian male patient were examined in order to elucidate the cause of his infertility. A detailed examination of the variation in cilia and spermatozoa of control subjects was also conducted. The axonemal structure of all nasal samples from control subjects showed a low frequency of abnormalities; however, when present, abnormalities varied between samples. The nasal cells and spermatozoa of the infertile patient were distinct from control samples, both in terms of motility and ultrastructure. The spermatozoa axonemes of the patient displayed the normal 9+2 microtubule ultrastructure; however, the proportion of immotile spermatozoa and ultrastructural abnormalities was higher than in control samples. All of the patient's nasal cilia were functionally immotile and approximately 70% of ciliated cells displayed extensive ciliary fusion; a feature not found in controls and not previously described. Despite having immotile nasal cilia, this patient was healthy with no obvious respiratory ailments. Additionally, the nasal cells of the patient possessed mitochondria with distended membranes, internalised membranous material, cilia with vesicles and internalised axonemes. These features suggest that ciliary deployment and membrane deposition was compromised in the patient

Environmental adaptation in stomatal size independent of the effects of genome size

Cell sizes are linked across multiple tissues, including stomata, and this variation is closely correlated with genome size. These associations raise the question of whether generic changes in cell size cause suboptimal changes in stomata, requiring subsequent evolution under selection for stomatal size. We tested the relationships among guard cell length, genome size and vegetation type using phylogenetically independent analyses on 67 species of the ecologically and structurally diverse family, Proteaceae. We also compared how genome and stomatal sizes varied at ancient (among genera) and more recent (within genus) levels. The observed 60-fold range in genome size in Proteaceae largely reflected the mean chromosome size. Compared with variation among genera, genome size varied much less within genera (< 6% of total variance) than stomatal size, implying evolution in stomatal size subsequent to changes in genome size. Open vegetation and closed forest had significantly different relationships between stomatal and genome sizes. Ancient changes in genome size clearly influenced stomatal size in Proteaceae, but adaptation to habitat strongly modified the genome-stomatal size relationship. Direct adaptation to the environment in stomatal size argues that new proxies for past concentrations of atmospheric CO2 that incorporate stomatal size are superior to older models based solely on stomatal frequency.Gregory J. Jordan, Raymond J. Carpenter, Anthony Koutoulis, Aina Price and Timothy J. Brodrib

Red to far-red ratio correction in plant growth chambers - growth responses and influence of thermal load on garden pea

Plant growth chambers are commonly used to minimize environmental variation but the light sources used vary considerably from natural light and from each other. Incandescent globes are often used to add more far-red light, with the aim of producing a more natural red to far-red ratio (R:FR), but also add to thermal load. High-intensity discharge lamps are often used to produce higher irradiances, more akin to natural light, but the thermal implications are rarely considered because air temperature is controlled. This paper examines the spectral properties and thermal implications of growth chamber light sources and takes a whole-plant physiology approach, by examining growth responses of a photoperiodic pea line (Pisum sativum L. cv. Torsdag) in the same growth chamber type under different light sources – in essence using plants to study the controlled environments rather than vice-versa. High R:FR delayed flowering and inhibited internode extension in pea. However, the addition of far-red-rich incandescent globes in the proportions provided in the growth chambers (400–500 W) did little to reduce R:FR, did not induce earlier flowering and actually further inhibited internode length. Leaflet size and yield were significantly reduced. While air temperature was maintained at 20C in all experiments, radiant temperature was significantly higher under high irradiance and/or with incandescent added, and soil temperatures were elevated. Growth responses under these lights were similar to the effect caused by elevating the air temperature. An alternative method of controlling R:FR, without thermal load implications, using light-emitting diodes is described