The Vascular Anatomy of the Barley Spikelet

In the spikelet axis of Proctor spring barley there was a coreof vascular tissue in which the normal collateral bundle structurewas not distinguishable. From this tissue the vascular strandsbranched out, in sequence, to the sterile lateral spikelets,the glumes, the lemma, the palea, the lodicules and the stamens.The vascular tissue of the spikelet axis terminated in the ovaryin four bundles of which the adaxial bundle passing close tothe ovule was the biggest. The arrangement of the vascular strandsand the presence of transfer cells indicated that assimilate,particularly from the lemma, can be easily translocated to thegrowing grain. In the collar region the spikelets, which inthe mature ear bear small grains, were less well vas-cularized. In the vascular tissue beneath the ovary were thick-walled cells.These cells and the cells of the funiculus-chalaza region maybe important in the process of translocation and grain growth.     

Besnoitia darlingi (Brumpt, 1913) in Panama

SYNOPSIS. Besnoitia darlingi (Brumpt, 1913) Mandour, 1965 has been rediscovered in the common opossum Didelphis marsupialis in the Republic of Panama. A strain (D3) has been established in laboratory white mice. Proliferative crescents of the D3 strain are 6.1 (range 6.0-9.0) by 2.1 (range 1.7-4.0).
Mouse-adapted B. darlingi produced acute, fatal infections in white mice, hamsters, 14 marmosets ( Saguinus geoffroyi ), 2 squirrels ( Sciurus variegatoides and S. granatensis ), a woolly opossum ( Caluromys derbianus ) and a four-eyed opossum ( Philander opossum ) It probably produced chronic infections (cysts) in 2 wild-caughtopossums ( Didelphis marsupialis ) and one lizard ( Ameiva ameiva ). Animals in which induced infection could not be found after inoculation with trophozoites of mouse-adapted B. darlingi were: 2 adult and 2 new-born guinea pigs, laboratory rats, 1 night monkey ( Aotus trivirgatus ), 2 rhesus monkeys ( Macacca mulatta ), one iguana ( Iguaanaiguana ) and 2 baby caimans ( Caiman sclerops ).     

Duthieeae,a new tribe of grasses (Poaceae) identified among the early diverging lineages of subfamily Pooideae: molecular phylogenetics,morphological delineation,cytogenetics and biogeography

The phylogeny of Pooideae, one of the largest subfamilies of grasses, has been intensively studied during the past years. To investigate the early evolutionary splits in Pooideae we used a broad sample of genera with uncertain placement, some of which have not been studied in molecular phylogenetics before, complemented by representatives from other lineages of this subfamily. Morphological, cytogenetic and biogeographical analyses were added to the molecular sequence work on chloroplast matK–3’trnK and nuclear ITS. According to chloroplast DNA data, a new and well-supported lineage was identified among the early branches. It consisted of Phaenosperma and a larger group of genera encompassing Anisopogon, Danthoniastrum, Duthiea, Metcalfia, Pseudodanthonia (inclusion resting on ITS and morphology), Sinochasea and Stephanachne. Based on structural characters we suggest to keep Phaenosperma under the monotypic tribe Phaenospermateae and to accommodate the other genera under a new tribe Duthieeae, which is morphologically well-defined by synapomorphic spikelet features. Megalachne and Podophorus were not part of the early diverging Pooideae lineages but belong to the Aveneae/Poeae complex. Morphological characteristics of Duthieeae are discussed with respect especially to Stipeae and reveal consistent differences between both tribes. The genera of Duthieeae and the major lineages of Stipeae are keyed. A cytogenetic survey of exemplary taxa corroborates high chromosome base numbers as prevailing within the early diverging lineages of Pooideae, but chromosome sizes are more highly varied than previously reported. Ecogeographical analyses point to warm and humid conditions as the ancestral bioclimatic niche of Phaenosperma and Duthieeae, whereas adaptation to cold and drought occurred only in a part of Duthieeae but was obviously less successful than in the widespread and much more species-rich tribe Stipeae. The distribution of Duthieeae with species-poor or monotypic genera in mountains of the northern hemisphere and Anisopogon as an outlier in Australia suggests relict character.     

Dermal armour histology of aetosaurs (Archosauria: Pseudosuchia), from the Upper Triassic of Argentina and Brazil

Cerda, I.A. & Desojo, J.B. 2010: Dermal armour histology of aetosaurs (Archosauria: Pseudosuchia), from the Upper Triassic of Argentina and Brazil. Lethaia, Vol. 44, pp. 417–428. One of the most striking features documented in aetosaurs is the presence of an extensive bony armour composed of several osteoderms. Here, we analyse the bone microstructure of these elements in some South American Aetosaurinae aetosaurs, including Aetosauroides scagliai. In general terms, Aetosaurinae osteoderms are compact structures characterized by the presence of three tissue types: a basal cortex of poorly vascularized parallel‐fibred bone tissue, a core of highly vascularized fibro‐lamellar bone, and an external cortex of rather avascular lamellar bone tissue. Sharpey’s fibres are more visible at the internal core, toward the lateral margins and aligned parallel to the major axis of the dermal plate. No evidence of metaplastic origin is reported in the osteoderms, and we hypothesize an intramembranous ossification for these elements. The bone tissue distribution reveals that the development of the osteoderm in Aetosaurinae starts in a position located medial to the plate midpoint, and the main sites of active osteogenesis occur towards the lateral and medial edges of the plate. The osteoderm ornamentation is originated and maintained by a process of resorption and redeposition of the external cortex, which also includes preferential bone deposition in some particular sites. Given that no secondary reconstruction occurs in the osteoderms, growth marks are well preserved and they provide very important information regarding the relative age and growth pattern of Aetosaurinae aetosaurs. □Aetosauria, Aetosauroides, Archosauria, bone microstructure, integumentary skeleton, osteoderm.     

Patterns of local and regional genetic structuring in the meadow grasshopper,Chorthippus parallelus (Orthoptera: Acrididae), in Central Germany revealed using microsatellite markers

The meadow grasshopper, Chorthippus parallelus (Zetterstedt), is common and widespread in Central Europe, with a low dispersal range per generation. A population study in Central Germany (Frankenwald and Thüringer Schiefergebirge) showed strong interpopulation differences in abundance and individual fitness. We examined genetic variability using microsatellite markers within and between 22 populations in a short‐ to long‐distance sampling (19 populations, Frankenwald, Schiefergebirge, as well as a southern transect), and in the Erzgebirge region (three populations), with the latter aiming to check for effects as a result of historical forest cover. Of the 671 C. parallelus captured, none was macropterous (functionally winged). All populations showed a high level of expected and observed heterozygosity (mean 0.80–0.90 and 0.60–0.75, respectively), whereas there was evidence of inbreeding (F_IS values all positive). Allelic richness for all locus–population combinations was high (mean 9.3–11.2), whereas alleles per locus ranged from 15–62. At a local level, genic and genotypic differences were significant. Pairwise F_ST values were in the range 0.00–0.04, indicating little interpopulation genetic differentiation. Similarly, the calculated gene flow was very high, based on the respective F_ST (19.5) and using private alleles (7.7). A Neighbour‐joining tree using Nei's D_A and principal coordinate analysis separated two populations that were collected in the Erzgebirge region. Populations from this region may have escaped the effects of the historical forest cover. The visualization of the spatial arrangement of genotypes revealed one geographical barrier to gene flow in the short‐distance sampling. © 2011 The Linnean Society of London, Biological Journal of the Linnean Society, 2011, 103 , 875–890.