Transformation of the filamentous fungus Gibberella fujikuroi using the Aspergillus niger niaD gene encoding nitrate reductase

Summary A transformation system for Gibberella fujikuroi based on the Aspergillus niger nitrate reductase gene (niaD) was developed. A strain (designated SG140) carrying a non-reverting niaD mutation (niaD11) was generated by screening mutagenised cells for non-growth on nitrate as sole nitrogen source. Transformation frequencies of 1–2 transformants per g DNA were observed when strain SG140 was transformed to nitrate utilisation. Southern blot analyses of niaD⁺ transformants showed that the vector DNA sequences were integrated into the chromosomal DNA. The results demonstrate that the A. niger niaD gene is expressed in G. fujikuroi.     

Immunocytochemical identification of structures containing putative red pigment-concentrating hormone in two species of decapod crustaceans

Summary By use of an antiserum raised against the Nterminal sequence pGlu-Leu-Asn-Phe..., common to red pigment-concentrating hormone (RPCH) of Pandalus borealis and three structurally similar insect neuropeptides, putative RPCH-immunopositive structures were revealed in the eyestalks of Carcinus maenas and Orconectes limosus and in the brain and thoracic ganglion (TG) of C. maenas. In the eyestalks, complete neurosecretory pathways were demonstrated, consisting of perikarya, axons and terminals in the neurohemal organ, the sinus gland (SG). In C. maenas approximately 20 small RPCH cells are present as a distinct group adjacent to the medulla terminalis ganglionic X-organ (MTGXO, XO). They are morphologically different from the larger XO perikarya, which contain the crustacean hyperglycemic hormone (CHH). The occurrence of both neuropeptides in distinct neurosecretory pathways was ascertained by immunologic double staining (PAP/gold) or by analysis of consecutive sections. In addition, a group of two to four larger RPCH cells is located in the proximal part of the MT. In O. limosus, RPCH cells are found in the XO. Cells corresponding to the proximal MT cells of C. maenas were not found. In both species, a few more weakly staining immunopositive perikarya were observed in clusters of cell somata of the optic ganglia. It is uncertain whether these are connected to the SG.In the brain of C. maenas, several smaller and three larger perikarya were consistently observed in the dorsal lateral cell somata adjacent to the olfactory lobes. In the optic nerve, two axons that project into the eyestalk were stained. Some axons were also observed in the ventral median neuropil of the brain. In the TG, RPCH cells were found in small numbers in median positions, i.e., in clusters of somata between the ganglia of the appendages.HPLC analysis of the red pigment-concentrating activity from the SG of C. maenas revealed that the retention time of the neuropeptide is similar but not identical to that of Pandalus borealis RPCH.     

Protective effects of sarpogrelate, a 5-HT2A antagonist, against postischemic myocardial dysfunction in guinea-pig hearts

The protective effects of sarpogrelate (SG), a 5-HT_2A antagonist, were investigated in perfused guinea-pig Langendorff hearts subjected to ischemia and reperfusion. Changes in cellular levels of high phosphorous energy, NO and Ca²⁺ in the heart together with simultaneous recordings of left ventricular developed pressure (LVDP) were monitored using an nitric oxide (NO) electrode, fluorometry and ³¹P-NMR. The recovery of LVDP from ischemia by reperfusion was 30.1% in the control, while the treatment with SG (5×10^-7 M) in pre- and post-ischemia hearts produced a gradual increase to 73.1 and 53.6%, respectively. At the final stage of ischemia, the intracellular concentration of Ca²⁺ ([Ca²⁺_i) and release of NO increased with no twitching and remained at a high steady level. The addition of SG increased the transient NO signal (T_NO) level at the end of ischemia compared with the control, but [Ca²⁺]_i during ischemia decreased. Meanwhile, mitochondrial Ca²⁺ uptake on acidification or Ca²⁺ content changes of the perfusate was suppressed by pre-treatment with SG or the K_ATP channel opener diazoxide, but not the K_ATP channel blocker 5-HD. The myocardial NO elevated with 5-HT in normal Langendorff hearts was suppressed by the treatment with SG. Therefore, the existence of the 5HT_2A receptor in a Langendorff heart was anticipated. By in vitro EPR, SG was found to directly quench the hydroxy radical. Thus, these findings suggested that the 5-HT_2A receptor induced in ischemia–reperfusion plays an important role in the mitochondrial K_ATP channel of hearts in close relation with NO and active oxygen radicals.     

Effectiveness of the cleaning performance of the bacterial strain <Emphasis Type="Italic">Acinetobacter</Emphasis> sp. SG06-02 in the petroleum hydrocarbon-polluted intestine of clams

Summary A petroleum-degrading bacterial strain Acinetobacter sp. SG06-02 in the oil-polluted intestine of shellfish clam was previously isolated in our laboratory. In this study, the effectiveness of using its cleaning performance on petroleum pollution was investigated. The accumulation of petroleum in the intestine of Ruditapes philippinarum was determined by a UV spectrophotometer. The survival and growth of the SG06-02 strain in the intestine of Ruditapes philippinarum after oil pollution were examined. The concentration of oil accumulated in the Ruditapes philippinarum intestine quickly rises to 254.97 mg/kg within 12 h after placing the clam in the petroleum-polluted seawater tank. After decontaminating using Acinetaobacter we found that the concentration of petroleum inside the Ruditapes philippinarum declined significantly. The results of the cleaning experiments showed that the degradation activity by using bioremediation method of the strain SG06-02 increased 12.8∼30.2% compared to using clean seawater in 4 days. This research indicated that the petroleum degrading bacteria could survive and was effective in cleaning oily pollutants in the seashell.     

Immunocytochemical localization of pigment-dispersing hormone (PDH) and its coexistence with FMRFamide-immunoreactive material in the eyestalks of the decapod crustaceans Carcinus maenas and Orconectes limosus

Summary By use of a new antiserum, raised against synthetic pigment-dispersing hormone (PDH) from Uca pugilator, immunoreactive structures were studied at the light-microscopic level in the eyestalk ganglia of Carcinus maenas and Orconectes limosus. PDH-reactivity was mainly found in two types of neurons that were located between the medulla interna (MI) and the medulla terminalis (MT) in both species. Several additional perikarya were located in the distal part of the MI in O. limosus. In C. maenas, two to three PDH-positive perikarya were found in the region of the X-organ (XO) in the MT. Processes from single and clustered cells could be traced into all medullae of the eyestalk. Axons from the immunoreactive perikarya running between MI and MT form a larger tract that traverses the MT. Fibers from this tract give rise to extensive arborizations and plexuses throughout the proximal MT. A plexus containing very fine fibers is located at the surface of the MT in a position distal to the XO-area of C. maenas only. The proximal plexus also receives PDH-positive fibers through the optic nerve. PDH-perikarya in the cerebral ganglion may also project into the more distal regions of the eyestalk. Distal projections of the perikarya between the MI and MT consist of several branches. Most of these are directed toward the MI and ME (medulla externa) wherein they form highly organized, layered plexuses. One branch was traced into the principal neurohemal organ, the sinus gland (SG). In the SG, the tract gives off arborizations and neurosecretory terminals. It then proceeds in a proximal direction out of the SG, adjacent to the MT. Its further course could not be elucidated. The lamina ganglionaris (LG) receives PDH-fibers from the ME and fine processes from small perikarya located in close association with the LG in the distal part of the first optic chiasma. The architecture of PDH-positive elements was similar in both C. maenas and O. limosus. The distribution of these structures suggests that PDH is not only a neurohormone but may, in addition, have a role as a neurotransmitter or modulator. Immunostaining of successive sections with an FMRF-amide antiserum revealed co-localization of FMRFamideand PDH-immunoreactivities in most, but not all PDH-containing perikarya and fibers. The axonal branch leading to the SG and the SG proper were devoid of FMRFamide immunoreactivity.     

Zero order kinetics of cell wall turnover inStaphylococcus aureus

Cells exponentially grown from four strains ofS. aureus (SG 511, H, 52A5G, and248 PN-1) and uniformly labeled in their walls with³H-N-acetylglucosamine, were found to turn over their old walls at constant rates of up to 25% per generation. Wall turnover was not observed to follow first order kinetics, thus ruling out the implication that maintenance of normal wall thickness was achieved by a random distribution of new wall components in the old wall. Instead, wall turnover in all cases strictly followed zero order kinetics, indicating that newly synthesized wall material was placed layer by layer beneath the inner surface of the old cell wall. This finding correlates with evidence obtained from earlier electron microscopic investigations into the regeneration of the staphylococcal cell wall after chloramphenicol treatment. Based on the experimental data presented, a simplified model for wall turnover of the growing staphylococcal cell was proposed. The model also takes into account the finding, derived from additional experiments with strainSG 511, that the total cell wall turned over at a somewhat higher rate than the old portions of the wall. The rates of cell wall turnover found inS. aureus SG 511 are the highest reported to date for pathogenic bacteria. The medical implications of this finding were discussed.     

Alterations in the structure of phycobilisomes of the cyanobacterium,Spirulina platensis in response to enhanced Na+ level

Incubation of Spirulina platensis at enhanced Na⁺ concentrations resulted in 30% increased intracellular accumulation of Na⁺ ions. This accumulation of Na⁺ ions intracellularly altered the phycobilisome organization as revealed by transmission electron microscopic data and changes in the absorption spectrum. The room temperature emission peak at 638 nm in the control sample was blue-shifted by 7 nm in the treated samples suggesting phycobilisome disorganization. SDS-PAGE of phycobilisome polypeptides showed a significant increase in a 66.2 kDa polypeptide. This is the first report that the enhanced concentration of intracellular Na⁺ ion alters the structure of the phycobilisome in S. platensis. This revised version was published online in November 2006 with corrections to the Cover Date.     

Tilletiopsis derxii, Tilletiopsis oryzicola and Tilletiopsis penniseti, three new species of the ustilagionomycetous anamorphic genus Tilletiopsis isolated from leaves in Thailand

Four strains of ballistoconidium-forming yeast-like fungi (K-95, K-125, K-132 and K139), isolated from plants collected in Bangkok, Thailand, were assigned to the genus Tilletiopsis based on morphological and chemotaxonomical characteristics. On the basis of sequence data of 18S rDNA and the D1/D2 region of 26S rDNA, strains K-95, K-125 and K-132 were close to T. flava and T. fulvescens, and strain K-139 each formed related to T. minor. DNA-DNA reassociation experiments with related species revealed that strains K-125, K-132 and K-139 each formed a new and distinct species whereas strain K-95 was identified as T. flava. Tilletiopsis derxii Takashima et Nakase sp. nov. (JCM 10217^T; K-125), Tilletiopsis oryzicola Takashima et Nakase sp. nov. (JCM 10218^T; K-132), and Tilletiopsis penniseti Takashima et Nakase sp. nov. (JCM 10216^T; K-139) are the names proposed for the new taxa.     

Infectivity, growth, development and pathology of Echinostoma caproni (Trematoda) in the golden hamster

Laboratory hamsters (Mesocricetus auratus) were experimentally infected with 75 ± 15 metacercarial cysts of Echinostoma caproni. Worms were recovered from days 7 to 89 post-infection with eight to 90 (average 37) parasites in the small intestine. Worm wet weights averaged 0.85 mg at 10 days, 1.8 mg at 17 days, 3.4 mg at 45 days, and 7.7 mg at 89 days; average dry weights for the identical days were, 0.15, 0.30, 0.70 and 2.2 mg, respectively. The average body area of worms fixed in hot (80°C) alcohol-formalin-acetic acid was 0.21 mm² on day 3, 4.9 mm² on day 10, and 17.7 mm² on day 42. Clinical signs in some hamsters included progressive unthriftiness and watery diarrhea. Gross examination revealed enlarged lymphatic nodules along the length of the small intestine. The histopathological responses of hamsters to the parasite showed erosion of the intestinal villi with lymphocytic infiltration being the primary response; hemorrhagic areas were also observed in the villi.     

Endocrinological investigation into the reproductive cycles of two sympatric skate species, Malacoraja senta and Amblyraja radiata, in the western Gulf of Maine

The smooth skate, Malacoraja senta, and thorny skate, Amblyraja radiata, are two commercially exploited batoids found within the Gulf of Maine. During the past five years, we conducted a large study to accurately describe important biological life history parameters previously lacking for these species. As part of that project, the current study reports our findings on the hormonal profiles associated with the reproductive cycles of M. senta and A. radiata. Blood samples were obtained from mature M. senta and A. radiata of both sexes from all months of the year, and plasma testosterone (T), estradiol (E₂) and progesterone (P₄) concentrations were determined using radioimmunoassay (RIA). In female M. senta and A. radiata, monthly T concentrations ranged from 4,522 pg ml⁻¹ to 1,373 pg ml⁻¹ and 31,940 pg ml⁻¹ to 14,428 pg ml⁻¹, E₂ concentrations from 831 pg ml⁻¹ to 60 pg ml⁻¹ and 8,515 pg ml⁻¹ to 2,902 pg ml⁻¹, and P₄ concentrations from 3,027 pg ml⁻¹ to 20 pg ml⁻¹ and 3,264 pg ml⁻¹ to 331 pg ml⁻¹, respectively. No statistical differences were detected between any months for any hormone. Estradiol concentrations were not correlated with ovary weight, shell gland weight, or diameter of the largest follicles in either species. Monthly T concentrations in male M. senta and A. radiata ranged from 23,146 to 12,660 pg ml⁻¹ and from 57,500pg ml⁻¹ to 24,737 pg ml⁻¹, while E₂ concentrations ranged from 7.5 pg ml⁻¹ to undetectable and 103 to 30 pg ml⁻¹, respectively. No statistical differences were observed between months for either steroid. Testosterone concentrations were weakly correlated with testes weight and percent of stage VI spermatocysts in A. radiata, however, no correlation was detected between T and stage VI spermatocysts in M. senta. Collectively, these data support the previous conclusion that M. senta and A. radiata of both sexes are capable of reproducing year round in the western Gulf of Maine.     

Inheritance of body color in the brown planthopper, Nilaparvata lugens

The segregation frequencies of color phenotypes of F₁, F₂, and backcross progenies revealed that the body coloration of the brown planthopper, Nilaparavata lugens(Stål), exhibited multiple allelism. Monogene for color morphism exists in three allelic forms >-b ⁺ (brown or wild type), b ^o (orange) and b ^b (black). The dominance relationship was b ^b>b ⁺>b ^o. The relationship between phenotype and genotype in N. lugens was not fixed. The six possible genotypes produced eight phenotypes.

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Résumé Les fréquences de ségrégation des différentes colorations de F₁, F₂ et des croisements en retour ont montré que la coloration du corps de Nilaparvata lugens est due à un multi-allèlisme. Le monogène pour la couleur existe sous trois formes allèliques: b⁺ (brun ou sauvage), b^o (orange) et b^b (noir). Les relations de dominance étaient: b^b>b⁺>b^o. On n'a pas établi les relatios entre phénotypes et génotypes chez N. lugens. Les 6 génotypes possibles produisent 8 phénotypes.

     

Effects of N-deficiency and timing of N supply on the recovery and distribution of labeled 15N in contrasting maize hybrids

Little information exists on the pattern of nitrogen (N) uptake, remobilization and N use efficiency (NUE) in Leafy and stay-green (SG) maize (Zea mays L.) genotypes. A pot experiment was conducted under controlled nutrition and growing conditions to determine the response of Leafy and SG maize genotypes to different levels of N-deficiency and timing of N supply. Three contrasting maize hybrids, Pioneer 3905 (a conventional hybrid with moderate SG characteristics), Pioneer 39F06 Bt (with a high score of SG trait) and Maizex LF850-RR (with a Leafy trait) were grown in 6 L plastic pots. Five different N treatments [no supply of N until V8 (N₁), no supply of N after V8 (N₂), no supply of N after silking (N₃), no supply of N beyond 3 weeks after silking (N₄), and continuous N supply from emergence to physiological maturity (N₅; standard check)] were imposed through modified Hoagland solution applied manually. Labeled ¹⁵N of 5% ¹⁵N₂–NH₄NO₃fertilizer was applied at 3 g per pot at the start of each schedule N treatment. Total amounts of N applied in different treatments were 3.13, 1.32, 1.90, 2.63 and 3.40 g, respectively in N₁, N₂, N₃, N₄ and N₅. Dry matter, N concentration, ¹⁵N (atom% enrichment) and NUE were determined in roots, stalk, leaves and grains at crop maturity. The three contrasting hybrids did not differ in grain yield, total N acquisition, partitioning of ¹⁵N and NUE. Restriction of N supply until V8, and from V8 to physiological maturity significantly reduced grain yield and N-uptake in all hybrids. Irrespective of the level of N-deficiency in plant and timing when the labeled fertilizer was applied, the amount of ¹⁵N recovered in the matured plant was the same in all N treatments. It has been evident that maize continued to take up N beyond 3 weeks after silking and the later N was applied during the development, the higher proportion of it was partitioned to grains. Of the total ¹⁵N uptake, 78% was partitioned to kernels in the N₄ treatment compared to only 61% in the control. Our data showed no evidence of differential N uptake, remobilization and NUE in the SG or Leafy hybrids tested, but the timing of N application and level of N-deficiency in plant significantly influenced N uptake, remobilization and N-dynamics in maize.     

Immunostimulatory activity of sulfated galactans isolated from the red seaweed Gracilaria fisheri and development of resistance against white spot syndrome virus (WSSV) in shrimp

Sulfated galactans (SG) were isolated from the red seaweed Gracilaria fisheri (G. fisheri). Chemical analysis revealed SG contains sulfate (12.7%) and total carbohydrate (42.2%) with an estimated molecular mass of 100 kDa. Structure analysis by NMR and FT-IR spectroscopy revealed that SG is a complex structure with a linear backbone of alternating 3-linked β-d-galactopyranose and 4-linked 3,6-anhydrogalactose units with partial 6-O-methylate-β-d-galactopyranose and with sulfation occurring on C4 of d-galactopyranose and C6 of l-galactopyranose units. SG treatment enhanced immune parameters including total haemocytes, phenoloxidase activity, superoxide anions and superoxide dismutase in shrimp Penaeus monodon. Shrimp fed with Artemia salina enriched with SG (100 and 200 μg ml⁻¹) and inoculated with white spot syndrome virus (WSSV) showed a significantly lower mortality rate and lower viral VP 28 amplification and expression than control. The results suggest that SG from G. fisheri exhibits immune stimulatory and antiviral activities that could protect P. monodon from WSSV infection.     

Interactions between epsilon, the proofreading subunit of DNA polymerase III, and proteins involved in the SOS response of Escherichia coli

Summary Epsilon, a fidelity subunit of Escherichia coli DNA Polymerase III, is encoded by dnaQ ⁺. dnaQ49 is a recessive allele that confers temperature-sensitive and saltsuppressible phenotypes for both replication fidelity and viability. SOS mutagenesis in E. coli is regulated by LexA and requires activated RecA (RecA^*) and the products of the umuDC operon. dnaQ49 strains with various recA, lexA and umuDC alleles were constructed to determine if activities induced as part of the SOS response influence epsilon activity. We found: (1) both UmuDC and RecA^* independently enhance the dnaQ49 mutator phenotype, and (2) expression of RecA^* activity in the absence of UmuDC function increases the temperature sensitivity for viability of dnaQ49. These results support the hypothesis that RecA and one or both of the UmuDC proteins interact with the replication complex during SOS mutagenesis.     

Opioid peptides in the nervous system ofAplysia: A combined biochemical,immunocytochemical, and electrophysiological study

Summary 1. We have used biochemical, immunocytochemical, and electrophysiological techniques to evaluate the role of opioid peptides in the central nervous system of the marine mollusc,Aplysia california.2. Binding studies using³H-d-Ala², met-enkephalinamide (³H-DAMA) showed a single class of high-affinity binding sites with aK _d of 1.3 nM and a binding density of 45 pmol/g.3. HPLC extracts of ganglia revealed multiple peaks with immunoreactivity for either leu (LEU-IR)- or met-enkephalin (MET-IR), but the amounts were not uniformly distributed in all ganglia.4. LEU-IR and MET-IR neurons were demonstrated immunocytochemically in all ganglia, but MET-IR neurons were more frequent and were concentrated in pedal and pleural ganglia. While absorption control studies abolished MET-IR, LEU-IR was only partially abolished in the neuropil.5. In electrophysiological studies, both depolarizing and hyperpolarizing responses were found tod-Ala²-leu-enkephalin (DALEU) andd-Ala²-met enkephalin (DAMET) on some and different neurons.6. HPLC fractions from regions with retention times corresponding to authentic leu- or met-enkephalin showed physiologic responses similar to those of DALEU and DAMET, respectively.7. These studies suggest that a variety of endogeneous opioid peptides play physiologically important roles in the nervous system ofAplysia, including but not necessarily limited to leu- and met-enkephalin.     

Characterization of SLFL1, a pollen-expressed F-box gene located in the Prunus S locus

The S locus and its flanking regions in the genus Prunus (Rosaceae) contain four pollen-expressed F-box genes. These genes contain the S locus F-box genes with low allelic sequence polymorphism genes 1, 2, and 3 (SLFL1, SLFL2, and SLFL3) as well as the putative pollen S gene, named the S haplotype-specific F-box protein gene (SFB). As much less information is available on the function of SLFLs than that of SFB, we analyzed the SLFLs of six S haplotypes of sweet cherry (Prunus avium) in this study. Genomic DNA blot analysis and the isolation of SLFL1 showed that the SLFL1 gene in a functional self-incompatible S ³ haplotype is deleted and only a partial sequence resembling SLFL1 is left in the S ³ locus region, suggesting that SLFL1 by itself is not directly involved in either the GSI reaction or pollen-tube growth. Genomic DNA blot analysis showed that there was no substantial modification or mutation in SLFL2 and SLFL3. A phylogenic analysis of F-box genes in the rosaceous S locus and its border regions showed that Prunus SLFLs were more closely related to maloid S locus F-box brothers than to Prunus SFBs. The functions of SLFLs and the evolution of self-incompatibility in Prunus are discussed based on these results. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users. The nucleotide sequence data reported appear in the DDBJ, EMBL, and GenBank Nucleotide Sequence Databases under the accession numbers, AB360339, AB360340, AB360341, and AB360342, for SLFL1-S ¹ , SLFL1-S ² , SLFL1-S ⁵ , and SLFL1-S ⁶ , respectively.     

An extensive Cochlodinium bloom along the western coast of Palawan, Philippines

A massive fish kill and water discoloration were reported off the western coast of Puerto Princesa, Palawan, Philippines in March 2005. Phytoplankton analysis revealed a near monospecific bloom of the dinoflagellate, Cochlodinium polykrikoides, with cell concentrations ranging from 2.5 × 10⁵ to 3.2 × 10⁶ cells per liter. Ground truth data were supplemented by processed satellite images from MODIS Aqua Level 2 data (1 km resolution) from January to April 2005, which revealed high surface chlorophyll-a levels (up to 50 mg/m³) offshore of west and southwest Palawan as early as February 2005. The bloom extended 310 km in length and 80 km in width at its peak in March off the central coast (Puerto Princesa). By April, the bloom declined in intensity, but was still apparent along the northern coast (El Nido). Fluctuations in chlorophyll levels off the western coast of Sabah, Malaysia and Brunei during this time period suggested that the bloom was not limited to the coast of Palawan. Satellite imagery from Sabah in late January revealed a plume of chl-a that is believed to be the source of the C. polykrikoides bloom in Palawan. This plume drifted offshore, advected northward via the basin-wide counterclockwise gyre, and reached nutrient-rich, upwelled waters near Palawan (due to a positive wind stress curl) where the dinoflagellate bloomed and persisted for 2 months from March to April 2005.     

Distribution,community structure and production of fishes in the upper Speed River,Ontario: a preimpoundment study

Synopsis The upper Speed River, on which a dam was under construction, was surveyed through fourteen qualitative and six quantitative collections to determine the distribution of fishes in the river above Guelph, Ontario and in a tributary, Luteral Creek. At the quantitative localities the removal method was used to estimate density and standing crop of all species. At three of these localities age and growth of the dominant species were determined and total ecological production calculated. Two approaches to the estimation of production for the 0–1 age class were compared and found to result in differences of 33–39% in the estimates of total production, thus illustrating the extent to which methodology may affect such estimates The dominant species in the river were, Semotilus atromaculatus, Notropis cornutus, Pimephales notatus, Rhinichthys atratulus, Hypentelium nigricans, Catostomus commersoni, Ambloplites rupestris, Micropterus dolomieui and Etheostoma flabellare. Density ranged from 11126 to 74765 individuals per hectare and standing crop from 32.4 to 190.0 kg ha⁻¹. Production values at the three localities were 15, 19 and 54 kg ha⁻¹ yr⁻¹ , and are low compared with estimates for other fluvial systems. Comparison with a 1951 survey of the Speed River revealed considerable changes in the composition and distribution of fish species. The ranges of several cold-water species had contracted towards the headwaters, whereas several warm-water species had extended their ranges up the river     

Survival ofLegionella pneumophila in the aquatic environment

Survival ofLegionella pneumophila SG 1 in seawater and river water was assessed using plate counts on buffered charcoal yeast extract agar amended with α-ketoglutarate (BCYEα) and [³H]thymidine-labeling. The [³H]thymidine-labeling method for assessing survival ofL. pneumophila in aquatic environments was compared with viable counts, direct fluorescent microscopy (DFA), and acridine orange direct counts (AODC). Protozoa were isolated from the samples employed in the study and identified by characteristic trophozite and cyst morphology. Selective filtration employing 2.0 μm Nucleopore filters was used to determine the effect of grazing on survival ofL. pneumophila in seawater and river water.Legionella viability as measured by plate counts (CFU/ml), declined to a greater extent than cell lysis, assessed by thymidine, DFA, and AODC counts, suggesting thatL. pneumophila survives in aquatic habitats to a greater extent than revealed through culturable counts.