Wood and bark anatomy of the African species of Gnetum

Quantitative and qualitative data are given for the two African species of Gnetum ( Gnetum section Gnetum subsection Micrognemones ). These species are lianoid and lack the fibre-tracheids of G. gnemon but have about the same vessel element and tracheid length as in that species. Vessel diameter is related to stem age and organography. Tori are clearly present in tracheary elements of the African Gnetum species, a first report for the genus. In these two species, origin of the lateral meristem, which produces vascular tissue and cambia, can be traced directly and indirecdy to cortical parenchyma. A second kind of meristematic action, newly reported for Gnetum, is produced by proliferation of axial parenchyma, fragmenting secondary xylem. Both presence of tori and site of origin of lateral meristematic activity in Gnetum contrast with corresponding conditions in Welwitschia.     

Low genetic variability of the koala Phascolarctos cinereus in south-eastern Australia following a severe population bottleneck

Genotyping of koalas at CA-repeat microsatellite loci has revealed significant differences in the levels of allelic diversity ( A ) and expected heterozygosity ( H¯ _E) between populations from north-eastern and south-eastern Australia. In the 10 populations studied, allelic diversity ranged from 8.0 in the Nowendoc population to 1.7 in the Kangaroo Is. population, and values of H¯ _E ranged from 0.831 in the Nowendoc population to 0.331 in the Kangaroo Is. population. Data from pooled populations revealed koalas from the north-eastern region had significantly higher levels of allelic diversity ( A = 11.5 ± 1.4) than those from south-eastern Australia ( A = 5.3 ± 1.0). Furthermore significantly higher heterozygosity levels were found in the north-eastern ( H¯ _E= 0.851) vs. the south-eastern ( H¯ _E= 0.436) regions of Australia. Following a near-extinction bottleneck in the 1920s, mainland Victorian and Kangaroo Is. koalas have been involved in an extensive program of relocations. The source populations of the relocated animals were islands in Westernport Bay, which were founded by very few individuals in the late 1800s and early 1900s. The significantly lower levels of variation between south-eastern Australian populations suggests that human intervention has had a severe effect on levels of genetic diversity in this region, and this may have long-term genetic consequences.     

Phylogenetic Analysis of the Diplomonadida (Wenyon, 1926) Brugerolle, 1975: Evidence for Heterochrony in Protozoa and Against Giardia lamblia as a "Missing Link"

ABSTRACT. A suite of 23 ultrastructural characters was used in a phylogenetic analysis of the protozoan order Diplomonadida. A single most parsimonious solution was found, with a length of 38 transformations and a consistency index of 0.84. The cladogram supports previous hypotheses of the relationships of the genera in the suborder Diplomonadina, as well as the inclusion of the genera Enteromonas and Trimitus in the order. Heterochrony is suggested in the change to binary axial symmetry, as hypermorphosis resulting from delayed cytokinesis in the ancestor. Hypotheses regarding a pivotal position for Giardia lamblia in the evolution of eukaryotes are inconsistent with the phylogeny proposed here.     

Recent Advances in Our Knowledge of the Myxozoa

In the last few years two factors have helped to significantly advance our understanding of the Myxozoa. First, the phenomenal increase in fin fish aquaculture in the 1990s has lead to the increased importance of these parasites; in turn this has lead to intensified research efforts, which have increased knowledge of the development, diagnosis. and pathogenesis of myxozoans. The hallmark discovery in the 1980s that the life cycle of Myxobolus cerebralis requires development of an actinosporean stage in the oligochaete. Tubifex tubifex, led to the elucidation of the life cycles of several other myxozoans. Also, the life cycle and taxonomy of the enigmatic PKX myxozoan has been resolved: it is the alternate stage of the unusual myxozoan, Tetracapsula bryosalmonae, from bryozoans. The 18S rDNA gene of many species has been sequenced, and here we add 22 new sequences to the data set. Phylogenetic analyses using all these sequences indicate that: 1) the Myxozoa are closely related to Cnidaria (also supported by morphological data); 2) marine taxa at the genus level branch separately from genera that usually infect freshwater fishes; 3) taxa cluster more by development and tissue location than by spore morphology; 4) the tetracapsulids branched off early in myxozoan evolution, perhaps reflected by their having bryozoan, rather than annelid hosts; 5) the morphology of actinosporeans offers little information for determining their myxosporean counterparts (assuming that they exist); and 6) the marine actinosporeans from Australia appear to form a clade within the platysporinid myxosporeans. Ribosomal DNA sequences have also enabled development of diagnostic tests for myxozoans. PCR and in situ hybridisation tests based on rDNA sequences have been developed for Myxobolus cerebralis, Ceratomyxa shasta, Kudoa spp., and Tetracapsula bryosalmonae (PKX). Lectin-based and antibody tests have also been developed for certain myxozoans, such as PKX and C. shasta. We also review important diseases caused by myxozoans, which are emerging or re-emerging. Epizootics of whirling disease in wild rainbow trout (Oncorhynchus mykiss) have recently been reported throughout the Rocky Mountain states of the USA. With a dramatic increase in aquaculture of fishes using marine netpens, several marine myxozoans have been recognized or elevated in status as pathological agents. Kudoa thyrsites infections have caused severe post-harvest myoliquefaction in pen-reared Atlantic salmon (Salmo salar), and Ceratomyxa spp., Sphaerospora spp., and Myxidium leei cause disease in pen-reared sea bass (Dicentrarchus labrax) and sea bream species (family Sparidae) in Mediterranean countries.     

Logistic regression in comparative wood anatomy: tracheid types, wood anatomical terminology, and new inferences from the Carlquist and Hoekman southern Californian data set

Despite collecting copious amounts of data, wood anatomists rarely perform appropriate statistical analyses, especially in the case of categorical variables. Nevertheless, anatomists have succeeded in identifying strong ecological trends. We show that, with only a slightly more sophisticated analysis, the strength and significance of 'well-known' associations can be quantified, and new associations pinpointed. Using logistic regression to reanalyse the classic Carlquist and Hoekman data set for the southern Californian flora, we show strong support for the notion that true tracheid presence lowers vessel grouping; in contrast, vasicentric tracheids are associated with a diversity of vessel grouping strategies. We show that statistical models can refine anatomical interpretations by identifying unusual species. For example, Fremontodendron californicum and Baccharis salicifolia (=  B. glutinosa ) were identified as unusual in lacking vasicentric tracheids; a consultation of preparations revealed that they are indeed present. For purposes of ecological wood anatomy, anatomical terminology should reflect cell function; we suggest that terminological systems that yield better predictive power in statistical models such as ours are preferable. Finally, we make recommendations ranging from the statistical, e.g. the need to check assumptions and the need for the inclusion of phylogeny, to the biological, e.g. gathering data expressly designed to test functional hypotheses rather than all of the information in standardized lists.  © 2007 The Linnean Society of London, Botanical Journal of the Linnean Society , 2007, 154 , 331–351.     

VNTR loci reveal differentiation between and structure within populations of the eastern barred bandicoot Perameles gunnii

The Eastern Barred Bandicoot Perameles gunnii has declined in abundance within mainland south-eastern Australia, to a relict wild population of less than 100 individuals in Hamilton, Victoria. It is more common, but is also declining in Tasmania. Genomic DN A variability was compared within and between surviving populations of P. gunnii using variable number of tandem repeat (VNTR) markers in one of two ways. First, average percentage differences (APDs) were determined between profiles for two VNTR probe—endonuclease combinations. Secondly, because one of these combinations revealed two multiallelic VNTR loci, genotypes were assigned and analysed for homogeneity of allele frequencies among subpopulations, for deviation of heterozygosity from Hardy-Weinberg equilibrium within populations and for genetic structuring among individuals from different subpopulations. The results of both the APD and defined locus approaches showed consistent trends within and between populations. Genetic variability was higher among mainland P. gunnii than in Tasmanian populations (higher APDs, number of alleles, and heterozygosity at one locus), despite the known decline and subdivision of the Hamilton population. Eleven per cent of the variability detected in Hamilton was attributed to genetic differentiation between east and west subdivisions of the population. Departure from random mating indicating local inbreeding within collecting localities was evident for one locus in both north and south Tasmania, particularly at one locality. AH alleles at both loci were unique to either Hamilton or Tasmanian P. gunnii. The initial captive colony contains high heterozygosity for these loci. It is concluded that VNTR markers can be of benefit for use in studies of population differentiation and for conservation management.     

Assembly of the Paraflagellar Rod and the Flagellum Attachment Zone Complex During the Trypanosoma brucei Cell Cycle

Trypanosomes possess a single flagellum that is attached to their cell body via the flagellum attachment zone (FAZ). The FAZ is composed of two structures: a cytoplasmic filament complex and four microtubules situated next to it. There is a complex transmembrane crosslinking of this FAZ to the paraflagellar rod (PFR) and axoneme within the flagellum. We have partially purified the FAZ complex and have produced monoclonal antibodies both against the FAZ and the paraflagellar rod. The two antibodies against the FAZ (L3B2 and L6B3) recognise the cytoplasmic filament in immunofluorescence and in immunoelectron microscopy. On western blot, they detect a doublet of high molecular weight (M(r) 200,000). Two anti-PFR antibodies (L13D6 and L8C4) recognise the paraflagellar rod in immunofluorescence, but show a difference on Western blot: L13D6 recognises both major PFR proteins, whereas L8C4 is specific for only one of them. Using these new antibodies we have shown that although the growth of both cytoplasmic FAZ filament and external PFR are related, their growth initiates at different time points during the cell cycle and the two structures elongate at distinct rates.     

The Appearance of Lactic Acid in Phaseolus Seeds Germinating under Wet Conditions

Under normal conditions of germination, there is never muchlactate in bean cotyledons, but when beans are germinated underwet conditions lactate accumulates for about 30 h and then slowlydisappears, as radicle emergence begins. Removal of the testaefrom soaked seeds prevents subsequent lactate accumulation.Lactate also appears in beans germinated under nitrogen. Lactate dehydrogenase activity is enhanced in wet or anaerobicconditions. Incubation with pyruvate increased lactate dehydrogenaseby 50 per cent. There was also a temporary accumulation of alcohol in beansgrown under wet conditions. Under wet conditions the production of respiratory carbon dioxidewas particularly slow during the period of lactate accumulation.     

Wood anatomy of Krameriaceae with comparisons with Zygophyllaceae: phylesis, ecology and systematics

Wood of nine species of Krameria (including all clades proposed within the genus) reveals a few characters related to infrageneric systematics; most relate primarily to ecology and habit. Wood of Krameria closely fits quantitative data reported for desert shrubs. Lack of vessel grouping correlates with the presence of densely pitted tracheids. Wood xeromorphy in Krameria may relate in part to hemiparasitism. Tracheid presence may also account for relatively low vessel density. Wood anatomy of six species of Zygophyllaceae (including both genera of Morkillioideae) is compared with that of Krameriaceae because recent phylogenies propose that these two families comprise the order Zygophyllales. Several wood characters appear to represent synapomorphies reflecting this relationship. Differences in wood anatomy between Krameriaceae and Zygophyllaceae are believed to represent autapomorphies. Notable among these include Paedomorphic Type II rays (Krameriaceae), storying (Zygophyllaceae), presence of vestured pits (Zygophyllaceae), and differentiation into vasicentric tracheids and fibre-tracheids (Zygophyllaceae). The latter feature is referable to the concept of fibre-tracheid dimorphism. Recognition of Krameriaceae as separate from Zygophyllaceae is supported by wood characters. Wood of Zygophyllales does not conflict with the idea that the order belongs to rosids, with Malpighiaceae as the outgroup of Zygophyllales.  © 2005 The Linnean Society of London, Botanical Journal of the Linnean Society , 2005, 149 , 257–270.     

Collecting mammalian tissue and data for genetic studies

It is now recognized that genetic data have an important role in the management of wild and captive populations. Valuable samples and data can often be obtained when animals are handled for other reasons, but unless the personnel involved are aware of the correct procedures, the sample taken will probably be useless. This article outlines appropriate procedures, and the data that can be obtained from them, so that when an opportunity arises, a quick decision can be made about feasibility of sampling and the usefulness of the data for management or research. This paper does not cover the veterinary aspects of obtaining the sample, nor its laboratory analysis, which are assumed to be well understood by the donor and recipient organizations, respectively. Every attempt has been made to develop techniques which are simple, and allow storage of the sample while arrangements are made with a suitable recipient laboratory.