Seed dispersal of Korean pine Pinus koraiensis labeled by two different tags in a northern temperate forest, northeast China

Two types of tagging methods, i.e., a 1 × 3-cm tin tag attached to seed with a 10- to 12-cm metal wire (total weight 0.32 g) and a 2 × 4-cm white plastic tag fastened to seed with an identical metal wire (total weight 0.57 g) were used to study their effects on seed dispersal of Korean pine by small rodents. A total of 600 seeds were released to assess four main points: (1) difference in seed survival rates, (2) difference in caching behaviors of small rodents, (3) difference in dispersal distances, and (4) proportion of seed missing. The results demonstrated that seed removal for wire-plastic-tagged seeds was faster than that for wire-tin-tagged seeds. There was no apparent difference in the proportion of seeds eaten in situ (42% and 52% for wire-plastic-tagged seeds and wire-tin-tagged seeds, respectively). We found 41% and 1% of seeds were moved and hoarded for wire-plastic-tagged seeds and wire-tin-tagged seeds, respectively. However, 2.33% and 14% of seeds were missing, and their ultimate fates were not known for wire-plastic-tagged seeds and wire-tin-tagged seeds, respectively. We found the wire-plastic-tagged seeds easier to track than the wire-tin-tagged seeds due to the fact that the white plastic tags were more salient than the tin tags in field environments. The average dispersal distances were 4.11 ± 2.40 m and 3.01 ± 2.06 m for wire-plastic-tagged seeds and wire-tin-tagged seeds, respectively, and showed great difference. Despite most being eaten in situ or after removal, 41% of seeds were cached for wire-plastic-tagged seeds, much more than for wire-tin-tagged seeds. A total of 71 primary caches (123 seeds) were found for wire-plastic-tagged seeds, with the average and maximum cache sizes being 1.73 and 6, respectively. However, only three caches were found, and cache size was equal to one for wire-tin-tagged seeds. The above data suggests there is some uncertainty in different tagging methods to used track seed fates. Despite their effectiveness in helping to trace seed dispersal or movement by seed-dispersing rodents, different tagging methods—including size, color, and mass—need to be fully understand in enclosure experiments .     

Cost-effective HLA typing with tagging SNPs predicts celiac disease risk haplotypes in the Finnish, Hungarian, and Italian populations

Human leukocyte antigen (HLA) genes, located on chromosome 6p21.3, have a crucial role in susceptibility to various autoimmune and inflammatory diseases, such as celiac disease and type 1 diabetes. Certain HLA heterodimers, namely DQ2 (encoded by the DQA1*05 and DQB1*02 alleles) and DQ8 (DQA1*03 and DQB1*0302), are necessary for the development of celiac disease. Traditional genotyping of HLA genes is laborious, time-consuming, and expensive. A novel HLA-genotyping method, using six HLA-tagging single-nucleotide polymorphisms (SNPs) and suitable for high-throughput approaches, was described recently. Our aim was to validate this method in the Finnish, Hungarian, and Italian populations. The six previously reported HLA-tagging SNPs were genotyped in patients with celiac disease and in healthy individuals from Finland, Hungary, and two distinct regions of Italy. The potential of this method was evaluated in analyzing how well the tag SNP results correlate with the HLA genotypes previously determined using traditional HLA-typing methods. Using the tagging SNP method, it is possible to determine the celiac disease risk haplotypes accurately in Finnish, Hungarian, and Italian populations, with specificity and sensitivity ranging from 95% to 100%. In addition, it predicts homozygosity and heterozygosity for a risk haplotype, allowing studies on genotypic risk effects. The method is transferable between populations and therefore suited for large-scale research studies and screening of celiac disease among high-risk individuals or at the population level. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users. Lotta Koskinen and Jihane Romanos are authors with equal contribution.     

Patterns of nocturnal movement of the long-spined sea urchin<Emphasis Type="Italic"> Diadema antillarum</Emphasis> (Philippi) in Gran Canaria (the Canary Islands,central East Atlantic Ocean)

We tagged individuals of the sea urchin Diadema antillarum (Philippi) around the island of Gran Canaria (The Canary Islands) during winter 2001–2002 using a new technique, consisting of the insertion of a hook fastened to a fishing line into the aboral pole (periproctal membrane). This allowed individual identification of tagged sea urchins. The goals were: (1) to quantify nocturnal movements and the homing behaviour of this echinoid on shallow rocky bottoms, and (2) to assess short term spatial and temporal variability of these movements. Tagged sea urchins displayed clear homing behaviour. The mean distance travelled at night was 3.7±1.2 m (range 1.0–5.1 m). Mean speed of nocturnal movement was 33±26 cm h^–1 (range 5–110 cm h^–1). We observed greater movement at midnight than at the beginning and the end of the night.Communicated by H.-D. Franke     

植物抗病基因克隆研究进展

随着分子生物学及其相关技术的飞速发展,人们对植物与病原微生物相互作用的分子机制了解得越来越透彻。本文对植物过敏性反应和系统获得抗性作了简要概述,并着重讨论了植物抗病基因克隆的进展,涉及到转座子标签技术、定位克隆技术、染色体步行、染色体登陆等方法和策略,归纳了克隆到的植物抗病基因及其产物结构,概述了这些基因产物所共有的特点,并简要介绍了植物抗病基因工程的进展。     

Fluctuations in the muskellunge (Esox masquinongy Mitchill) population of Chautauqua Lake,New York

Synopsis Population and exploitation estimates were made from angler recaptures of Chautauqua Lake muskellunge,Esox masquinongy Mitchill. Fish were tagged during Conservation Department studies in 1941–1946, 1961–1965 and 1976–1978. Population estimates of adult fish ranged from one to seven fish per hectare and angler exploitation rates of tagged fish fluctuated from 3.8% to 14.1%. Relative catch indicators suggest a major decline in the lake's muskellunge population during the last decade. Overexploitation, habitat alteration and interspecific competition with recently introduced fish species were cited as probable causes of the decline.     

Alternative fates of paused ribosomes during translation termination

The bacterial tmRNA·SmpB system facilitates recycling of stalled translational complexes in a process termed "ribosome rescue." During ribosome rescue, the nascent chain is tagged with the tmRNA-encoded ssrA peptide, which targets the tagged polypeptide for degradation. Translational pausing also induces a variety of recoding events such as frameshifts, ribosome hops, and stop codon readthrough. To examine the interplay between recoding and ribosome rescue, we determined the various fates of ribosomes that pause during translation termination. We expressed a model protein containing the C-terminal Asp-Pro nascent peptide motif (which interferes with translation termination) and quantified the protein chains produced by recoding and ssrA-peptide tagging. The nature and extent of translational recoding depended upon the codon for the C-terminal Pro residue, with CCU and CCC promoting efficient +1 frameshifting. In contrast, ssrA-peptide tagging was unaffected by C-terminal Pro coding. Moreover, +1 frameshifting was not suppressed by tmRNA·SmpB activity, suggesting that recoding and ribosome rescue are not competing events. However, cells lacking ribosomal protein L9 (ΔL9) exhibited a significant increase in recoding and a concomitant decrease in ssrA-peptide tagging. Pulse-chase analysis revealed that pre-termination ribosomes turn over more rapidly in ΔL9 cells, suggesting that increased recoding alleviates the translational arrest. Together, these results indicate that tmRNA·SmpB does not suppress transient ribosome pauses, but responds to prolonged translational arrest.     

Growth,survival, and tag retention of steelhead trout (<Emphasis Type="Italic">O. mykiss</Emphasis>) surgically implanted with dummy acoustic tags

Recent advances in micro-electronics make the study of the migration of even small marine animals (>12 cm) over many 1000s of kilometres a serious possibility. Important assumptions in long-term studies are that rates of tag loss caused by mortality or tag shedding are low, and that the tagging procedure does not have an unacceptable negative effect on the animal. This paper reports results from a study to examine the retention of relatively large (24 × 8 mm) surgically-implanted dummy acoustic tags over a 7-month period in steelhead pre-smolts (O. mykiss), and the effects of implantation on growth and survival. Although there was some influence on growth to week 12, survival was high for animals > 13 cm FL. In the following 16-week period, growth of surgically implanted pre-smolts was the same as the control population and there was little tag loss from mortality or shedding. Currently available acoustic tags can be implanted in salmonid fish ≥12 cm FL, although combined losses from mortality and tag shedding were 33–40% for animals in the 12 and 13 cm FL size classes. By 14 cm FL, combined rates of tag loss (mortality plus tag shedding) for surgically implanted tags dropped to <15% and growth following surgery was close to that of the controls. Our results suggest that studies of ocean migration and survival over periods of many months are now feasible even for animals as small as salmon smolts. Surgically implanted salmon smolts are therefore good candidates for freshwater and coastal ocean-tracking studies on relatively long time scales (months). On such time scales, even relatively small salmon smolts may move thousands of kilometers in the ocean.     

KHARON1 Mediates Flagellar Targeting of a Glucose Transporter in Leishmania mexicana and Is Critical for Viability of Infectious Intracellular Amastigotes

The LmxGT1 glucose transporter is selectively targeted to the flagellum of the kinetoplastid parasite Leishmania mexicana, but the mechanism for targeting this and other flagella-specific membrane proteins among the Kinetoplastida is unknown. To address the mechanism of flagellar targeting, we employed in vivo cross-linking, tandem affinity purification, and mass spectrometry to identify a novel protein, KHARON1 (KH1), which is important for the flagellar trafficking of LmxGT1. Kh1 null mutant parasites are strongly impaired in flagellar targeting of LmxGT1, and trafficking of the permease was arrested in the flagellar pocket. Immunolocalization revealed that KH1 is located at the base of the flagellum, within the flagellar pocket, where it associates with the proximal segment of the flagellar axoneme. We propose that KH1 mediates transit of LmxGT1 from the flagellar pocket into the flagellar membrane via interaction with the proximal portion of the flagellar axoneme. KH1 represents the first component involved in flagellar trafficking of integral membrane proteins among parasitic protozoa. Of considerable interest, Kh1 null mutants are strongly compromised for growth as amastigotes within host macrophages. Thus, KH1 is also important for the disease causing stage of the parasite life cycle.     

Releasing of the European sea bass Dicentrarchus labrax (Linnaeus) in the Adriatic Sea: Large-volume versus intensively cultured juveniles

The main goals of this project were to evaluate if artificial reefs are suitable sites for releasing hatchery-reared sea bass and if intensively and extensive large-volume cultured sea bass are suitable to be released into the wild for stock enhancement purposes. Large-volume cultured bass were reared in lower densities compared to intensively cultured ones and, when fry were about 90 days old, were transferred into external ponds connected to the channels of the surrounding marsh, where that they could integrate pellet food sources with live prey. Intensively cultured bass were fed for 55 days with Artemia salina (Linnaeus, 1758) and then with pellets. Underwater visual census (UVC) and fishing sampling were carried out to verify the presence of the tagged specimens at the artificial reef. A low mortality rate after tagging was observed and good tag retention was recorded. Individuals dead after tagging were statistically smaller than survivors. A total of 45 tagged bass (42 large-volume and 3 intensively cultured) were returned by fishers and 16 specimens were observed during UVC (15 large-volume and 1 intensively cultured). The majority of recaptured bass concentrated in the surroundings of river mouths and harbours suggesting that, after release, sea bass migrated towards shallower and brackish waters. Subsequently, as they grew, they came back towards deeper waters and tended to aggregate around artificial structures. Analysis of stomach contents of returned individuals confirmed their dependence on hard-substrate food items. The study provides evidence to support the suitability of large-volume juveniles for restocking purposes, due to their ability to prey on wild food and their endurance to the stress caused by release operations.