Reassignment of Lamanema from Nematodirinae to Molineinae (Nematoda: Trichostronglyloidea)

The monospecific Lamanema historically has been assigned to the Nematodirinae within the Molineidae. Inconsistencies in morphological characters, within a phylogenetic context for Nematodirinae, led to a re-evaluation of the putative relationships and taxonomic placement of Lamanema. Among 7 putative synapomorphies for Nematodirinae, Lamanema possesses only 1, large eggs. Large eggs, sporadically present in phylogenetically disparate taxa of trichostrongyles, are equivocal with respect to placement of Lamanema; it is considered that possession of this single homoplasious character alone is insufficient justification to retain the genus in Nematodirinae. Affinities with the Trichostrongylidae (Cooperiinae or Haemonchinae) have also been proposed; however, Lamanema possess neither of 2 synapomorphies that diagnose monophyly of the family. Lamanema is retained in the Molineidae and transferred to the Molineinae as it possesses all characters of the family as currently defined. The origin of Lamanema represents a secondary colonization of ruminants by molineids and provides no context for elucidating the history of the Nematodirinae and Nematodirus.     

Evaluation of host preferences by helminths and ectoparasites among black-tailed jackrabbits in northern California

Fifty-four black-tailed jackrabbits (Lepus californicus) (five juvenile males, 22 adult males, five juvenile females, and 22 adult females) from Humboldt County, California (USA) were evaluated for sex and age-specific differences in parasite prevalences and intensities, 26 February through 30 October 1996. Nematodes found included Biogastranema leporis in 42 hares (78% prevalence), Rauschia triangularis in 26 hares (48%), Trichostrongylus calcaratus in 14 hares (26%), and Trichuris sylvilagi in two hares (4%). Cestodes found included Taenia sp. cysticerci in five hares (9%) and Taenia sp. coenurus found in one hare (2%). Ectoparasites found included the ticks Dermacentor variabilis on 10 hares (19%) and Ixodes spinipalpis (= Ixodes neotomae) on nine hares (17%), as well as the anoplurid louse Haemodipsus setoni on 12 hares (22%). No significant differences in the parasite prevalences or intensities were found between male and female jackrabbits; this was for all males and females collectively, juvenile males and females only, as well as adult males and females only. Combining male and female hosts, adult jackrabbits had a significantly higher prevalence of B. leporis and R. triangularis compared to juveniles. This is the first known report of Trichostrongylus calcaratus, Rauschia triangularis, Trichuris sylvilagi, and Dermacentor variabilis among black-tailed jackrabbits and the first known report of T. calcaratus and T. sylvilagi in the western USA. This is the first published report of I. spinipalpis, the vector for Lyme disease in California, on black-tailed jackrabbits.     

Influence of growth environment on coaggregation between freshwater biofilm bacteria

AIM: To characterize the expression of coaggregation between Blastomonas natatoria 2.1 and Micrococcus luteus 2.13 following growth in liquid culture, on agar and in an artificial biofilm matrix composed of poloxamer hydrogel. METHODS AND RESULTS: The ability of B. natatoria 2.1 and M. luteus 2.13 to coaggregate with one another was assessed following growth in liquid culture as colonies on agar or within a poloxamer hydrogel matrix. In all these environments a cycle of gain and loss of coaggregation occurred when the two cell types were aged simultaneously, with optimum expression occurring in early stationary phase. Blastomonas natatoria 2.1 cells only coaggregated maximally after entry into stationary phase. Conversely, M. luteus 2.13 cells only coaggregated in exponential phase and early stationary phase and coaggregation ability was lost in late stationary phase. Maximal coaggregation therefore only occurred between the two strains if both were in early stationary phase, when the surface properties of the two cell types were optimal for coaggregation. CONCLUSION: In addition to occurring between cells grown in liquid culture, coaggregation between aquatic bacteria occurs after growth as a biofilm on agar and in an artificial biofilm matrix in poloxamer. Under all conditions, the B. natatoria 2.1 coaggregation adhesin and complementary receptor on M. luteus 2.13 were only expressed simultaneously during early stationary phase.     

Numerical analysis of reflectance spectra

(1) Samples of yeast which varied over an arbitrary 0–100% scale with respect, to cytochrome concentration were prepared. (2) The reflectance spectrum of each sample was scanned. (3) These reflectance spectra were analyzed numerically on a digital computer to determine the bandwidths and intensities as a function of cytochrome concentration. Band shapes using the profiles of Cauchy, Gauss, and Giovanlelli were used. The correlations may be used to estimate cytochrome concentrations with a standard deviation of about 3%.