Morphology and aspects of growth of a trypanosome transmitted by the marine leech Johanssonia arctica (Piscicolidae) from Northern Norway

Abstract

Abstract. The fish leech Johanssonia arctica (Johansson, 1898) was collected from king crabs Paralithodes camtschaticus (Tilesius, 1815) in Finnmark, N Norway, and allowed to feed on experimental fish hosts in the laboratory. This leech ingested blood from laboratory-reared cod (Gadus morhua) and halibut (Hippoglossus hippoglossus). Some experimental halibut acquired trypanosome infection, with parasitaemia between ca. 500 and 60,000 trypanosomes ml -1 . The trypanosomes were of variable size and measured 39-90 µm (mean 57 µm) ca. 81 days post-infection. Characteristic features are cell striation, refractile cytoplasmic granules, anterior nucleus and a relatively long (ca. 6 µm, max 9 µm) distance from the posterior end to the kinetoplast. Following growth, the trypanosomes became increasingly slender, with fewer striae and a nucleus position less pronounced anterior. The trypanosome is considered distinct from a type transmitted by the leech Calliobdella nodulifera (Malm, 1863) in the NE Atlantic, but is regarded conspecific with a trypanosome transmitted by J. arctica in the NW Atlantic. This trypanosome has in the past been identified as Trypanosoma murmanensis Nikitin, 1927, a poorly described species. T. murmanensis cannot be recognized with certainty among the trypanosomes transmitted by C. nodulifera and J. arctica respectively. We propose that the J. arctica-transmitted species is considered T. murmanensis Nikitin, 1927 sensu stricto.

Trypanosomes infecting cod Gadus morhua L. in the North Atlantic: a resurrection of Trypanosoma pleuronectidium Robertson, 1906 and delimitation of T. murmanense Nikitin, 1927 (emend.), with a review of other trypanosomes from North Atlantic and Mediterranean teleosts

“…New primers were designed from these sequences (Table 2), and were used to amplify trypanosome SSU rDNA from samples of dried blood scraped off bloodsmears (with a sterile scalpel). These smears were unstained thin and thick blood/leucocyte smears of morphologically characterised trypanosomes from (i) wild cod (Table 1), (ii) smears from a cod experimentally infected with trypanosomes from the leech Calliobdella nodulifera (see Karlsbakk, 2004a) (DQ016614, DQ016615) and (iii) three halibut experimentally infected with trypanosomes from J. arctica (see Karlsbakk et al, 2005, halibut 1, 3-5) (DQ016616). The DNA templates were purified using the DNeasy protocol for animal tissues (Qiagen) according to the manufacturer instructions.…”

“…In addition, anterior cytoplasm tends to be finely granular, with series of small sometimes longitudinally arranged vacuoles. There are no detectable chromophilic granules, yellow pigment granules or refractive granules (sensu Laird, 1952;Khan, 1978;Karlsbakk et al, 2005).…”

“…T. pleuronectidium from Norwegian cod differs from the trypanosome vectored by Johnanssonia arctica in the NW Atlantic and N Norway (i.e. Karlsbakk et al, 2005;Khan, 1972Khan, , 1976Khan, , 1977, in its attained body length, PK length, NI, and in the lack of a prominent karyosome (Karlsbakk, 2004a, b;Karlsbakk et al, 2005; see below). Among the trypanosome species described early in the 20th Century from French waters, T. callionymi Brumpt & , T. cotti Brumpt & Lebailly, 1904, T. gobii Brumpt & Lebailly, 1904and T. laternae Lebailly, 1904 approach T. pleuronectidium in size.…”

“…Khan (1976) showed that this trypanosome is transmitted by the piscicolid leech Johanssonia sp., later identified as J. arctica (Johansson) (see Meyer & Khan, 1979). J. arctica from Northern Norway (Finnmark) was also found to transmit T. murmanense (sensu Khan, 1972Khan, , 1976Khan, , 1977 (see Karlsbakk, Haugen, & Nylund, 2005).…”

Morphological and genetic differences of Trypanosoma in some Chinese freshwater fishes: difficulties of species identification

“…Successful cross-transmission experiments have proven that particular trypanosome species are not restricted to the host species from which they were originally recovered (Lom 1973;Letch 1979;Woo and Black 1984), thus, refuting the host-specificity hypothesis. In addition, based on morphological criteria, Letch (1979) found that six fish species from different genus in British populations were infected with trypanosomes that were morphologically indistinguishable, and Karlsbakk et al (2005) found a trypanosome species transmitted by the marine leech from Northern Norway showing large disparities in morphology and aspects during different infection times. Moreover, most of the early descriptions are simple and inadequate according to current morphological standards (Smit et al 2004;Karbowiak et al 2005;Gu et al 2006bGu et al , 2007 and can hardly be used for a safe determination of species.…”