A Genetic and Chemical Perspective on Symbiotic Recruitment of Cyanobacteria of the Genus Nostoc into the Host Plant Blasia pusilla L.

Liverwort Blasia pusilla L. recruits soil nitrogen-fixing cyanobacteria of genus Nostoc as symbiotic partners. In this work we compared Nostoc community composition inside the plants and in the soil around them from two distant locations in Northern Norway. STRR fingerprinting and 16S rDNA phylogeny reconstruction showed a remarkable local diversity among isolates assigned to several Nostoc clades. An extensive web of negative allelopathic interactions was recorded at an agricultural site, but not at the undisturbed natural site. The cell extracts of the cyanobacteria did not show antimicrobial activities, but four isolates were shown to be cytotoxic to human cells. The secondary metabolite profiles of the isolates were mapped by MALDI-TOF MS, and the most prominent ions were further analyzed by Q-TOF for MS/MS aided identification. Symbiotic isolates produced a great variety of small peptide-like substances, most of which lack any record in the databases. Among identified compounds we found microcystin and nodularin variants toxic to eukaryotic cells. Microcystin producing chemotypes were dominating as symbiotic recruits but not in the free-living community. In addition, we were able to identify several novel aeruginosins and banyaside-like compounds, as well as nostocyclopeptides and nosperin.

Disease dynamics of red-spotted newts and their anuran prey in a montane pond community.

Long-term monitoring of amphibians is needed to clarify population-level effects of ranaviruses (Rv) and the fungal pathogen Batrachochytrium dendrobatidis (Bd). We investigated disease dynamics of co-occurring amphibian species and potential demographic consequences of Rv and Bd infections at a montane site in the Southern Appalachians, Georgia, USA. Our 3-yr study was unique in combining disease surveillance with intensive population monitoring at a site where both pathogens are present. We detected sub-clinical Bd infections in larval and adult red-spotted newts Notophthalmus viridescens viridescens, but found no effect of Bd on body condition of adult newts. Bd infections also occurred in larvae of 5 anuran species that bred in our fishless study pond, and we detected co-infections with Bd and Rv in adult newts and larval green frogs Lithobates clamitans. However, all mortality and clinical signs in adult newts and larval anurans were most consistent with ranaviral disease, including a die-off of larval wood frogs Lithobates sylvaticus in small fish ponds located near our main study pond. During 2 yr of drift fence monitoring, we documented high juvenile production in newts, green frogs and American bullfrogs L. catesbeianus, but saw no evidence of juvenile recruitment in wood frogs. Larvae of this susceptible species may have suffered high mortality in the presence of both Rv and predators. Our findings were generally consistent with results of Rv-exposure experiments and support the purported role of red-spotted newts, green frogs, and American bullfrogs as common reservoirs for Bd and/or Rv in permanent and semi-permanent wetlands.

A new Haemogregarina species of the alligator snapping turtle, Macrochelys temminckii (Testudines: Chelydridae), in Georgia and Florida that produces macromeronts in circulating erythrocytes.

Haemogregarina macrochelysi n. sp. (Apicomplexa: Haemogregarinidae) of the alligator snapping turtle, Macrochelys temminckii, is characterized by slender, recurved gamonts 29-35 x 3-4.5 microm, in which the anterior limb comprises 48-54% of the total length. The gamont nucleus, 5-7.5 x 2-5 microm, is situated at approximately midbody of the gamont. Meronts typical of Haemogregarina occupying erythrocytes have 3-8 small, compact nuclei and are 13-17 x 4.5-9 microm. Erythrocytic meronts that contain larger, nearly square or rectangular nuclei become rounded, and then undergo 7 or more nuclear divisions, which produce very large, usually ovoid to rounded meronts that may contain up to 150 nuclei or more within the thinly stretched host erythrocyte membrane. In tissues of the Placobdella spp. leech vectors, merogony occurs directly from sporozoites, forming merozoites that presumably are infective for the turtle host.

Health assessment of free-ranging alligator snapping turtles (Macrochelys temminckii) in Georgia and Florida.

The Alligator Snapping Turtle (Macrochelys temminckii) is a large freshwater turtle endemic to river systems that drain into the Gulf of Mexico. Turtle populations were sharply reduced by commercial harvest in the 1970s and 1980s; however, the species has yet to be protected under the Endangered Species Act. While anthropogenic stressors such as habitat fragmentation and degradation and illegal capture continue to threaten populations, the degree to which disease may be contributing to any decline of the Alligator Snapping Turtle is unknown. Data were collected from 97 free-ranging Alligator Snapping Turtles in nine waterways in Florida and Georgia from 2001 to 2006. Eleven turtles were captured more than once, resulting in a total sample pool of 123. Reference ranges were established for complete blood count, plasma biochemistry values, trace metals (mercury, zinc, copper, lead, and arsenic), and nutrient parameters (vitamins A, E, D, and selenium). Variations by capture location, sex, and season were detected and likely resulted from external factors such as habitat and diet. Turtles sampled in one location were positive for tortoise herpesviral antibodies. Blood mercury values also differed among populations. This study provides justification for the use of these long-lived aquatic turtles as biologic monitors of the health of local freshwater ecosystems.