Description of Paratetrahymena parawassi n. sp. using Morphological and Molecular Evidence and a Phylogenetic Analysis of Paratetrahymena and Other Taxonomically Ambiguous Genera in the Order Loxocephalida (Ciliophora,Oligohymenophorea)

ABSTRACT. The marine scuticociliate Paratetrahymena parawassi n. sp. is described on the basis of morphology, especially infraciliature, and the sequence of its small subunit (SSU) rRNA gene to become the second known member of its genus. Paratetrahymena and other ciliates in the order Loxocephalida possess a mixture of morphological and morphogenetic features characteristic of the subclasses Hymenostomatia and Scuticociliatia. Accordingly, we used SSU rRNA sequences to analyze the phylogeny of Paratetrahymena and three other loxocephalid genera. Paratetrahymena and Cardiostomatella vermiformis formed a moderately well‐supported clade that diverged at a deep level from all other scuticociliates, supporting separation of loxocephalids from other scuticociliates as a suprafamilial taxon. Sathrophilus holtae was a sister taxon to Paratetrahymena and Cardiostomatella in a poorly supported, unresolved relationship; nevertheless, association of all three genera into a single clade was supported by an approximately unbiased (AU) test. Any association of these genera singly or as a group with the Hymenostomatia was rejected decisively by AU tests and by a complete absence in the loxocephalids of the unique nucleotide identities that distinguish hymenostomes. Therefore, the morphological and morphogenetic similarities of loxocephalids to hymenostomes may be plesiomorphies, and the conflicting mix of scuticociliate and hymenostome characteristics seen in loxocephalids may result from differing rates of character evolution. Dexiotrichides pangi and Urocentrum, which is currently classified as a peniculid, formed a small clade that associated with hymenostomes and peritrichs. Monophyly of the Loxocephalida with Dexiotrichides and/or Urocentrum included was not rejected by AU; however, inclusion of Urocentrum in the Peniculia was rejected by AU tests. A hypothesis is offered to explain the lack of resolution of loxocephalid ciliates and Urocentrum in phylogenetic trees, namely that their phylogenetic positions are influenced by a combination of heterogeneous data and long‐branch attraction caused by poor representation of taxa in analyses. The well‐known genus Cyclidium, a member of the order Pleuronematida, was revealed to be polyphyletic as a byproduct of our analyses of loxocephalids. In particular, Cyclidium porcatum appears to fall outside the clade containing typical members of the subclass Scuticociliatia and thus invites investigation as a possible member of the order Loxocephalida.     

Vector competence of Coquillettidia linealis (Skuse) (Diptera: Culicidae) for Ross River and Barmah Forest viruses

Abstract Coquillettidia linealis is a severe pest on some of the Moreton Bay islands in Queensland, Australia, but little is known of its breeding habitats and biology. Because of its high abundance and its association with Ross River (RR) and Barmah Forest (BF) viruses by field isolation, its vector competence was evaluated in the laboratory by feeding dilutions of both viruses in blood. For RR, Cq. linealis was of comparable efficiency to Ochlerotatus vigilax (Skuse), recognised as being a major vector. Results were as follows for Cq. linealis and Oc. vigilax , respectively: dose to infect 50%, 10^2.2 and <10^1.7 CCID₅₀/mosquito; 88% and 90% disseminated infection at 4 days postinfection; transmission at 4 days with rates of 68−92% and 25−60%. For BF dose to infect 50%, 10^2.7 and 10^2.0; disseminated infection rates on first transmission day (day 6), 40% and 70%; transmission rates of 8−16% and 0−10%. As a capillary-tube method was used rather than suckling mice to demonstrate transmission, transmission rates may be underestimates. This, the first study of the vector competence of Cq. linealis in Australia, demonstrates that this species deserves control on the southern Moreton Bay islands.     

Calculation of collated indices of abundance of butterflies based on monitored sites

Abstract.

• 1 The Butterfly Monitoring Scheme uses regular transect counts on fixed sites to establish annual indices of abundance of butterfly species in the United Kingdom. The annual change in collated index for each species has hitherto been calculated as a simple ratio between total counts summed over all participating sites.
• 2 A revised method for calculation of collated indices is proposed, which applies a logarithmic transformation to site values so as to downweight the influence on the index of the sites with greatest numbers of a species. Zero counts are handled comparably with non-zero values. An alternative method using geometric mean ratios is also examined.
• 3 Indices calculated using the logarithmic transformation are compared with those calculated using the traditional method. Two internal tests of dependency of collated indices on the sites with highest abundance are made. Another evaluation uses regression analysis for the effects of temperature and rainfall on collated indices of butterfly abundance.
• 4 The first internal test shows that logarithmic transformation reduces the dependence of the collated index on the sites of highest abundance for twenty-five out of twenty-seven species examined; while a second test shows a reduction for twenty-six out of forty-two species, and an increase for one species. The number of significant regressions on temperature variables increases with the use of the logarithmic transformation from 11% to 13% of tests made, and on rainfall from 10% to 11%.
• 5 The geometric mean ratio method introduces considerable biases in its treatment of zero values, for which a remedy is not available.
• 6 Although the revised collated indices calculated using logarithmic transformation are broadly comparable with traditionally calculated values, the reductions in dependency on sites with the most abundant populations render the revised indices less subject to perturbation due to local ‘noise’, and so more suitable for research on factors influencing butterfly abundance.

     

Correlation of physical and biological properties of mouse mammary tumor agent

Biophysical procedures have been used to determine the size and structure of the biologically active agent responsible for the transmission, through milk, of mouse mammary adenocarcinoma. Filtration of milk from RIII high-breast-cancer mice through gradocol membranes with decreasing pore sizes indicated that a minimum of activity passed through intermediate pore sizes (100 to 160 mmicro). Filtrates through smaller pores were significantly active. Milk treated with small doses of deuteron irradiation produced more tumors than the control, unirradiated milk; larger doses indicated a particle size much less than 100 mmicro. Free diffusion experiments indicated that the activity was associated with particles of two different sizes. Altogether the data denoted the presence of a large agent about 100 mmicro in diameter and a small agent 20 to 30 mmicro in diameter or possibly smaller. Furthermore, the presence in the milk of an inhibitor 40 to 60 mmicro is indicated by the results of all three approaches. The complex nature of the milk agent disclosed by the physical measurements agrees with the picture of one of the structures revealed by electron microscopy as well as with seemingly conflicting measurements reported in the literature. The large agent defined by these indirect methods corresponds to the whole particle seen in the electron microscope and the small agent corresponds to its internal core or nucleoid. It is suggested that the nucleoid is essentially a nucleic acid which may, in the absence of the "inhibitor," retain its activity after being stripped of its outer membrane or sac.