Different thermostable DNA polymerases may amplify different RAPD products

Images

Determination of paternity in dragonflies by Random Amplified Polymorphic DNA fingerprinting

We used Random Amplified Polymorphic DNA (RAPD) fingerprinting to address issues of paternity in two odonate species. Amplification artifacts of RAPD markers were controlled by assessing paternity patterns relative to the banding patterns generated by quantitative mixtures of DNA from putative parents ('synthetic offspring'). In the aeshnid dragonfly Anax parthenope, for which the mating histories of both males and females were unknown, we found strong evidence for complete paternity success for the contact guarding male. In the highly polygamous libellulid dragonfly Orthetrum coerulescens, we detected and quantified mixed paternity in sequentially produced offspring clutches and demonstrated that fertilization success is correlated with the duration of copulation. Our results suggest that RAPD fingerprinting is suitable to address issues of paternity in systems which are genetically uncharacterized and produce large offspring clutches.

Class-level relationships in the phylum Cnidaria: evidence from mitochondrial genome structure

The phylogenetic relationships of the Recent cnidarian classes remain one of the classic problems in invertebrate zoology. We survey the structure of the mitochondrial genome in representatives of the four extant cnidarian classes and in the phylum Ctenophora. We find that all anthozoan species tested possess mtDNA in the form of circular molecules, whereas all scyphozoan, cubozoan, and hydrozoan species tested display mtDNA in the form of linear molecules. Because ctenophore and all other known metazoan mtDNA is circular, the shared occurrence of linear mtDNA in three of the four cnidarian classes suggests a basal position for the Anthozoa within the phylum.

Applications of random amplified polymorphic DNA (RAPD) in molecular ecology

Molecular genetic markers have been developed into powerful tools to analyse genetic relationships and genetic diversity. As an extension to the variety of existing techniques using polymorphic DNA markers, the Random Amplified Polymorphic DNA (RAPD) technique may be used in molecular ecology to determine taxonomic identity, assess kinship relationships, analyse mixed genome samples, and create specific probes. Main advantages of the RAPD technology include (i) suitability for work on anonymous genomes, (ii) applicability to problems where only limited quantities of DNA are available, (iii) efficiency and low expense.

Homeoboxes in cnidarians

Homeoboxes have previously been documented from various phyla of triploblastic, coelomate and pseudocoelomate, animals. We report here the first homeoboxes from cnidarians, a phylum of diploblastic organisms thought to occupy a near-basal position in metazoan phylogeny. We have sequenced three partial (77 bp) fragments of Antennapedia (Antp) class homeoboxes from the hydroids Hydractinia symbiolongicarpus and Eleutheria dichotoma. A pair of fragments, Cnox-2-Hs and Cnox-2-Ed, from the two species differ in nucleotide sequences but have identical derived amino acid sequences. A gene tree produced by parsimony analysis shows that these two fragments cluster within the Antp homeobox lineage. The third fragment, Cnox-1, clusters as a sister group of the other Antp class homeoboxes.

A Photoperiod Determined Life-Cycle in an Oligochaete Worm

For one common cosmopolitan naidid worm, Stylaria lacustris, we studied the effects of different environmental factors upon (1) the alternation of reproductive modes, (2) the rates of population increase, and (3) the combination of each of (1) and (2). While age, temperature, population density, or rate of feeding did not affect the mode of reproduction, photoperiod had a dominant effect. Under long-day conditions (LD > 12: 12), all worms reproduced exclusively by paratomic fission, theoretically ad infinitum. When transferred to short-day conditions (LD {le} 12:12) the worms ceased vegetative reproduction, and within 2 to 4 weeks developed the hermaphroditic genital apparatus and a clitellum. After an additional two weeks, the first cocoons were produced. The switch to the bisexual mode of reproduction was cum grano salis irreversible. These findings are consistent with observations of field samplings, and allow one to predict the annual life-cycle strategy of S. lacustris. This is the first example of a photoperiod determined life-cycle within the oligochaete worms. The vegetative mode of reproduction led to extremely high rates of population increase, whereas with the bisexual mode of reproduction the number of individuals was roughly stable. However, because S. lacustris could not withstand temperatures of 5{deg}C or lower, the switch to sexual reproduction and the formation of diapausing cocoons appear to be the only mechanism of overwintering. Nevertheless, some `asexual' clones never switch to sexual reproduction, whereas a loss of the asexual vegetative mode of reproduction did not occur. In contrast to some general predictions from life-history theories, the reproductive strategy of S. lacustris is highly preprogrammed and cannot respond to sudden and unexpected environmental changes.

Allometric changes during growth and reproduction in Eleutheria dichotoma (hydrozoa, athecata) and the problem of estimating body size in a microscopic animal

Changes in body morphology during growth and reproduction in the hydromedusa Eleutheria dichotoma are described in terms of variations in eight different characters: umbrella diameter, total surface area, tentacle area, umbrella area, tentacle knob diameter, number of embryos, and diameter and area of buds. Sexually (sex) and vegetatively (veg) reproducing medusae differ significantly in their body morphometrics. Statistically significant allometric relations exist between umbrella diameter and (1) central area (sex and veg); (2) tentacle area (veg); (3) total area (veg); (4) tentacle knob diameter (veg); (5) bud diameter; and (6) number of embryos. A significant correlation between umbrella diameter and area is also found in undetached buds. During sexual reproduction, umbrella area shows positive allometry and loses its correlations to total area, tentacle area, and tentacle knob diameter. Linear and nonlinear bivariate allometric coefficients allow estimation of total body size from only one or two easily measurable attributes, e.g., umbrella and tentacle knob diameter. Curve fitting by the classic allometric equation (y = bx^c ) is only negligibly worse than that obtained with a "full" equation (y = a + ^c ), and statistical confidence is better. Chemical analyses for carbon and nitrogen content allow estimation of biomass from the projection area of the body surface. The relation factors are 1.06 μgC mm^-2 (sex) and 1.14 μgC mm^-2 (veg) for carbon and 0.293 μgN mm^-2 (sex) and 0.287 μgN mm^-2 (veg) for nitrogen. The C:N ratios are 3.6 and 4.0 for sexual and vegetative medusae, respectively. The use of allometric regression formulas to calculate surface areas and to relate these to carbon content provides quick estimations of body size in a microscopic animal.

Energy costs of reproduction in the djungarian hamster Phodopus sungorus under laboratory and seminatural conditions

The aim of this study was to obtain ecologically relevant data on the rates and efficiencies of energy allocation to reproduction and to determine how laboratory data compare with data obtained under 'seminatural' conditions. Using the tritiated water (HTO) method we measured average daily metabolic rates (ADMRs) in Phodopus sungorus reproducing females over the whole period of pregnancy and lactation and in nonreproducing ones, under both laboratory and 'seminatural' conditions.Taking the difference in total energy expenditure between reproducing and nonreproducing females as the additional energy requirement for reproduction, it was found that the absolute energy expenditure for reproduction was independent of the experimental conditions used. For the production and nursing of one litter, Djungarian hamsters metabolized an additional 20.9 MJ kg^-1 in the laboratory, i.e. a 37% increase over normal maintenance expenditure, and 22.6 MJ kg^-1 under seminatural conditions, i.e. a 24% increase. The efficiency of litter production was estimated as 18.3% in the laboratory and as 16.4% under seminatural conditions. The differences between the two experimental conditions were not significant.