Acanthamoeba stevensoni N. Sp. (Protozoa: Amoebida) from Sewage-Contaminated Shellfish Beds in Raritan Bay, New York

Marine sediments from 12 shallow water stations in Raritan Bay, New York were tested for the presence of Acanthamoeba. Eight stations were positive for one or more species of Acanthamoeba, A. castellanii, A. comandoni, A. hatchetti, A. lenticulata, A. polyphaga, A. rhysodes, and Acanthamoeba spp. Isolates that grew at 38–40° C were found at four stations (A. comandoni, A. lenticulata, and two unidentified strains). The two unknown strains were characterized on the basis of morphological features, isoenzyme profiles, and mouse pathogenicity tests. One of the two strains was determined to be a new species and is designated herein as Acanthamoeba stevensoni n. sp., ATCC 50388. Mature cysts were most similar to those of morphological Group II of Pussard & Pons (1977). Acanthamoeba stevensoni n. sp. was isolated from inshore coastal sediments where seawater ranged from 20–30%‰ (ppt.). The sediments supported commercially valuable populations of hard clams, Mercenaria mercenaria, that required depuration prior to sale because of contamination by sewage-associated bacteria.     

Fish Tumor Pigment Cells: Differentiation and Comparison to Their Normal Counterparts

The objectives of this paper are to describe 1) the developmentof new research systems for biochemical comparison of cellulartraits between normal and tumorous pigment cells of fish origin,2) the similarity and dissimilarity between these two categoriesof pigment cells with regard to growth, differentiation andpigment translocating activities and 3) the potentials of thesetumorous pigment cells to manifest multiple differentiation.The development of research systems has been achieved by theestablishment of 1) methods to obtain homogenous populationsof viable, cultivatable xanthophores (erythrophores) and melanophoresfrom goldfish skins, 2) permanent cell lines from goldfish erythrophoromas(tumors derived from erythrophores) and from Nibe croaker irido-melanophoromas(tumors composed of mixed populations of iridophore- and melanophore-likecells) and 3) procedures to induce differentiation in normaland tumorous stem cells (including the formation of pigmentsand ability to undergo pigment translocation in response tocAMP, to the neurotransmitter epinephrine and to the hormonesACTH and melatonin). Two kinds of tumorous pigment cell linesexamined herein have the ability to form, in addition to variouspigments, structures similar to dermal skeletons and lentoidbodies. These findings strongly suggest the possibility thatthese fish pigment cell tumors are neural crest stem cell tumorsin nature.     

Simplified heavy metal staining techniques demonstrated with Fast Plant leaf tissue

Fast Plant(Brassica rapa,Cruciferae)leaf tissuefixed in glutaraldehyde-acrolein and post-fixed in os-mium,was examined for response to several easily-prepared heavy metal stains.Lead and uranium,separately and in combination,gave typical resultsacross the spectrum of cell organellets.As a single stainfollowing osmium,bismuth produced images seeminglyequivalent to lead and uranium.Phosphotungstic acidproduced very good membrane delineation but produceda washed-out background image similar to that from leadstaining.Carbohydrate compounds were especiallyresponsive to ruthenium;the cytoplasm and the matrixof all organelles were also stained very well.Theprocedures were no more demanding than traditionalstaining methods and may be easily used in research andteaching.Fast Plant materials are a reliable,quick andeasy source of living material.     

Effects of Pinealectomy and Ocular Enucleation on Diurnal Periodicity of Leucocytozoon smithi (Haemosporina) Gametocytes in the Peripheral Blood of Domestic Turkeys1

ABSTRACT. Domestic turkeys naturally infected with Leucocytozoon smithi were blinded by bilateral ocular enucleation, pinealectomized, sham-pinealectomized, pinealectomized plus enucleated, or maintained as controls. Groups of turkeys were acclimated to either light-dark periods of 14L:10D or “darkness” with intermittent periods (10–20 min) of red light at irregular hours approximately every three days as required for maintenance of turkeys. Peripheral gametocyte numbers of L. smithi in all groups were determined every 2 h over a 36 h period. Under 14L: 10D photoperiod, no observable difference in the pattern of gametocyte circadian rhythmicity between pinealectomized, enucleated, pinealectomized plus enucleated, and control turkeys was noted. Although mean parasitemias differed among groups, peak gametocyte numbers occurred between 1000 and 1800 h; how parasitemias occurred between 2000 and 0400 h. However, the phase of gametocyte rhythmicity in pinealectomized plus enucleated turkey hosts did exhibit a lag with reference to other hosts when examined by least squares fits of simple harmonics. Under conditions of “darkness” with intermittent, irregular periods of red light, L. smithi gametocyte numbers of individual turkeys, pinealectomized, sham-pinealectomized, or maintained as controls, exhibited a circadian periodicity though parasite cycles were out of phase with the natural photoperiod to which the turkeys previously had been exposed. A slight drift out of phase of L. smithi gametocyte periodicity occurred among turkeys in the sham-pinealectomized and the control groups while a considerably more prominent drift out of phase was seen among the parasite rhythmicity patterns of the pinealectomized birds. Data indicate that the pineal gland of the turkey did not directly mediate L. smithi gametocyte circadian periodicity, although an indirect involvement in regulating the timing of parasite rhythmicity is suggested.     

Bergmann's idiosyncratic rule: a role for fecundity selection?

The negative relationship between temperature and geographical variation in body size, or Bergmann's rule, is among the most thoroughly studied ecogeographical rules, yet the pattern and process underlying it remain controversial. Bergmann's original observations were of body size clines among endotherms, but in the last 50 years there has been increasing recognition that both Bergmann's rule and its reverse occur in many ectotherm taxa. A new study of syngnathid fish by Wilson (2009 ) in this issue of Molecular Ecology sheds light on intriguing alternative mechanisms that may explain variation in the direction of body size clines across taxa. Wilson shows that Bergmann's rule is found in pipefish of the genus Syngnathus , but not in seahorses of the genus Hippocampus . His results suggest that polygamy in pipefish allows fecundity selection to favour large size at low temperatures, compensating for increases in brooding time.     

Spatio-temporal variation in the strength and mode of selection acting on major histocompatibility complex diversity in water vole (Arvicola terrestris) metapopulations

Patterns of spatio-temporal genetic variation at a class II major histocompatibility complex (MHC) locus and multiple microsatellite loci were analysed within and between three water vole metapopulations in Scotland, UK. Comparisons of MHC and microsatellite spatial genetic differentiation, based on standardised tests between two demographically asynchronous zones within a metapopulation, suggested that spatial MHC variation was affected by balancing selection, directional selection and random genetic drift, but that the relative effects of these microevolutionary forces vary temporally. At the metapopulation level, between-year differentiation for MHC loci was significantly correlated with that of microsatellites, signifying that neutral factors such as migration and drift were primarily responsible for overall temporal genetic change at the metapopulation scale. Between metapopulations, patterns of genetic differentiation implied that, at large spatial scales, MHC variation was primarily affected by directional selection and drift. Levels of MHC heterozygosity in excess of Hardy–Weinberg expectations were consistent with overdominant balancing selection operating on MHC variation within metapopulations. However, this effect was not constant among all samples, indicating temporal variation in the strength of selection relative to other factors. The results highlight the benefit of contrasting variation at MHC with neutral markers to separate the effects of stochastic and deterministic microevolutionary forces, and add to a growing body of evidence showing that the mode and relative strength of selection acting on MHC diversity varies both spatially and temporally.