Environmental,geographical and time-related impacts on avian malaria infections in native and introduced populations of house sparrows (Passer domesticus), a globally invasive species

Aim

The increasing spread of vector-borne diseases has resulted in severe health concerns for humans, domestic animals and wildlife, with changes in land use and the introduction of invasive species being among the main possible causes for this increase. We explored several ecological drivers potentially affecting the local prevalence and richness of avian malaria parasite lineages in native and introduced house sparrows (Passer domesticus) populations.

Location

Global.

Time period

2002–2019.

Major taxa studied

Avian Plasmodium parasites in house sparrows.

Methods

We analysed data from 2,220 samples from 69 localities across all continents, except Antarctica. The influence of environment (urbanization index and human density), geography (altitude, latitude, hemisphere) and time (bird breeding season and years since introduction) were analysed using generalized additive mixed models (GAMMs) and random forests.

Results

Overall, 670 sparrows (30.2%) were infected with 22 Plasmodium lineages. In native populations, parasite prevalence was positively related to urbanization index, with the highest prevalence values in areas with intermediate urbanization levels. Likewise, in introduced populations, prevalence was positively associated with urbanization index; however, higher infection occurred in areas with either extreme high or low levels of urbanization. In introduced populations, the number of parasite lineages increased with altitude and with the years elapsed since the establishment of sparrows in a new locality. Here, after a decline in the number of parasite lineages in the first 30 years, an increase from 40 years onwards was detected.

Main conclusions

Urbanization was related to parasite prevalence in both native and introduced bird populations. In invaded areas, altitude and time since bird introduction were related to the number of Plasmodium lineages found to be infecting sparrows.     

Gathering and processing of lyme-grass (Elymus arenarius L.) in Iceland: an ethnohistorical account

Lyme-grass (Elymus arenarius L.) was harvested and processed for human consumption along the southern coast of Iceland until the beginning of this century. The origin of this exploitation is not known, but lyme-grass may have been gathered for this purpose already in the Viking Age. The system of processing lyme-grass is complex, and special implements and facilities are needed. The method is similar to traditional processing methods for cereals. Extensive research on Icelandic ethnographic observations was undertaken to establish the exact methods and sequence of operations that was involved. On the basis of this, a set of archaeological experiments was performed to test the viability of the processing techniques outlined in the written records. A model describing the harvesting and processing of lyme-grass is presented.     

Conservation of bronchiolar wall area during constriction and dilation of human airways

Mitchell, R. W., E. Rühlmann, H. Magnussen, N. M. Muñoz, A. R. Leff, and K. F. Rabe. Conservation ofbronchiolar wall area during constriction and dilation of humanairways. J. Appl. Physiol. 82(3):954-958, 1997.We assessed the effect of smooth musclecontraction and relaxation on airway lumen subtended by the internalperimeter(A_i)and total cross-sectional area (A_o)of human bronchial explants in the absence of the potential lungtethering forces of alveolar tissue to test the hypothesis thatbronchoconstriction results in a comparable change ofA_i andA_o.Luminal area (i.e.,A_i) andA_owere measured by using computerized videomicrometry, and bronchial wallarea was calculated accordingly. Images on videotape were captured;areas were outlined, and data were expressed as internal pixel numberby using imaging software. Bronchial rings were dissected in 1.0- to1.5-mm sections from macroscopically unaffected areas of lungs frompatients undergoing resection for carcinoma, placed in microplate wellscontaining buffered saline, and allowed to equilibrate for 1 h.Baseline, A_o[5.21 ± 0.354 (SE)mm²], andA_i(0.604 ± 0.057 mm²) weremeasured before contraction of the airway smooth muscle (ASM) withcarbachol. MeanA_inarrowed by 0.257 ± 0.052 mm²in response to 10 µM carbachol (P = 0.001 vs. baseline). Similarly, A_onarrowed by 0.272 ± 0.110 mm²in response to carbachol (P = 0.038 vs. baseline; P = 0.849 vs. change inA_i).Similar parallel changes in cross-sectional area forA_iandA_owere observed for relaxation of ASM from inherent tone of otherbronchial rings in response to 10 µM isoproterenol. We demonstrate aunique characteristic of human ASM; i.e., both luminal and totalcross-sectional area of human airways change similarly on contractionand relaxation in vitro, resulting in a conservation of bronchiolarwall area with bronchoconstriction and dilation.

     

Isolation of Pittsburgh pneumonia agent from a hospital shower.

Tatlockia (Legionella) micdadei, the Pittsburgh pneumonia agent, was isolated from a hospital shower. Although it was not possible, at the current time, to establish an epidemiological link to disease acquisition, this information may be significant because it provides further evidence that a water-associated reservoir of this organism exists within the hospital.     

Distinct genetic groups of Giardia intestinalis distinguished by restriction fragment length polymorphisms.

The taxonomic status of the parasitic protozoal species Giardia intestinalis depends on the morphological similarity of all Giardia isolated from humans and the presumption that Giardia are host-specific. On the basis of electrophoretic data derived from examination of 26 enzyme loci in Australian isolates, it has been proposed that G. intestinalis is a species complex comprising three or four genetically distinct (but morphologically cryptic) species. These received the tentative designations of genetic groups I-IV (R. H. Andrews, M. Adams, P. F. L. Boreham, G. Mayrhofer & B. P. Meloni. International Journal for Parasitology 19, 183-190, 1989). In the present study, two unrelated DNA probes (one specific for a gene encoding a trophozoite surface protein, the other detecting a non-coding repetitive sequence within the G. intestinalis genome) were used in Southern hybridization analyses to examine 10 axenic isolates of G. intestinalis, established from diverse geographical regions in Australia, together with the Portland-1 isolate from the USA. Both probes identified every isolate unambiguously as belonging to one or other of two genetic clusters. Electrophoretic analysis of the same samples indicated that these clusters correspond to the previously defined genetic groups I and II. No heterogeneity was apparent within the seven group I isolates using either probe. However, when probed with the repetitive sequence, the four isolates belonging to group II exhibited small differences in banding patterns, suggesting that this group may be less homogeneous than group I.(ABSTRACT TRUNCATED AT 250 WORDS)     

Isolating the influence of ontogeny helps predict island-wide variability in fish otolith chemistry

Reviews in Fish Biology and Fisheries - For marine fishes of commercial interest, defining how individuals vary in certain attributes, through ontogeny, and across space and time, can help expose...     

Some properties of turnip yellow mosaic virus isolated from hybrid Brassica Perko PVH in Yugoslavia

Anhand mikroskopischer Untersuchungen und durch Mittelversuche an A. pisum wurden folgende Kenntnisse zur Endosymbiose gewonnen:

• In L₃‐Stadien von A. pisum sind zwischen 55 und 85 potentielle Bakteriocyten vorhanden, von dene ca. 60–80 % besiedelt sind.

• Eine Reduktion des besiedelten Anteils in der F₁‐Generation auf unter 50% läßt eine deutliche Depression in der F₂‐Generation erwarten.

• Das Kriterium Embryonenlänge ist großen Schwankungen unterworfen und eignet sich nur bedingt als Unterscheidungsmerkmal.

• Die von Fröhlich (1990) vorgeschlagene Methodik zum Symbiontizidscreening bei A. pisum mit dem Standard OTC 2000 ppm und der Auszählung der mit TTC angefärbten Bakteriocyten unter dem Mikroskop läßt eine praktikable Testung von Substanzen auf symbiontizide Wirkung bei A. pisum zu. Es wird jedoch als günstiger angesehen, nicht die Larven mit den Pflanzen zu behandeln, wie von Fröhlich (1990) vorgeschlagen, sondern erst nach dem Antrocknen des Spritzbelages Adulte zur Erzeugung von F₁‐Larven anzusetzen.

• Es konnte eindeutig nachgewiesen werden, daß die von den Prüfsubstanzen hervorgerufenen aphiziden Effekte, insbesondere durch Cycloheximid (100/500 ppm) sowie Neemkernextrakt (50%), nicht auf einem symbiontiziden Wirkungsmechanismus beruhen (Ausnahme Oxytetracyclin 2000 ppm als Standard).

     

The effect of high pH on structural lipids in diatoms

We tested the hypothesis that increased pH reduces the amount of structural lipids. To do this, we used three different diatoms (Phaeodactylum tricornutum CCAP strain, P. tricornutum TV strain and Amphiprora sp). We tested the effect of rapid increase from pH?7.5 to 10 by adding NaOH. The total lipid content was reduced by 13, 36 and 47 % in the P. tricornutum CCAP strain, TV strain and Amphiprora sp., respectively, 1 h after increasing the pH. The P. tricornutum CCAP strain was used for further testing the effect of pH on the lipid content during active growth. This strain was cultivated at pH?7.5 and 10, and the pH was regulated by the CO₂ inflow. The growth rate was similar (0.3 day^?1) in both pH treatments, but the lipid content in the pH?10 treatment was on average 28 % lower than in the pH?7.5 treatment. Our data support the hypothesis that structural lipids are reduced when pH increases to high levels. The results suggest that regulating the pH during algae cultivation could be used to refine the lipid composition in the harvested algal biomass.     

Feeding ecology of mackerel and dietary overlap with herring in Icelandic waters

The Northeast Atlantic mackerel (Scomber scombrus) has been extending its summer feeding distribution north and west, including around Iceland, since around 2006. The objective of this study is to quantify the weight gain and total food consumption of mackerel and to evaluate the food competition between mackerel and herring (Clupea harengus) feeding in the marine ecosystem around Iceland during the summers 2009–2011. Mackerel feeding in Icelandic waters gained around 43% on average in weight during these summers. Based on swept-area abundance estimates of mackerel from an international survey in 2011 and available estimates of food conversion efficiency in mackerel, the weight gain in Icelandic waters in 2011 corresponded to a total consumption of around 3.4 (2.4?4.5) million tonnes. Overall, 98% of 2314 mackerel, 91% of 398 Icelandic summer-spawning herring and 96% of 424 Norwegian spring-spawning herring stomachs, collected over the summers 2009?2011, contained food. The mean weight of the stomach content of mackerel was higher than for herring in all the years. While the stomach content weight of mackerel was generally highest in southeastern and southwestern areas, it was highest for herring in western, eastern and northern areas. Analysis of stomach contents showed that Copepoda were the most important food of mackerel in most areas, while Copepoda and Euphausiacea were the most important food items for herring. Fish prey contributed a higher proportion in stomachs of mackerel than herring, although relatively low for both species.