Modelling fungal colonies and communities:challenges and opportunities

This contribution, based on a Special Interest Group session held during IMC9, focuses on physiological based models of filamentous fungal colony growth and interactions. Fungi are known to be an important component of ecosystems, in terms of colony dynamics and interactions within and between trophic levels. We outline some of the essential components necessary to develop a fungal ecology: a mechanistic model of fungal colony growth and interactions, where observed behaviour can be linked to underlying function; a model of how fungi can cooperate at larger scales; and novel techniques for both exploring quantitatively the scales at which fungi operate; and addressing the computational challenges arising from this highly detailed quantification. We also propose a novel application area for fungi which may provide alternate routes for supporting scientific study of colony behaviour. This synthesis offers new potential to explore fungal community dynamics and the impact on ecosystem functioning

Hsp90 Selectively Modulates Phenotype in Vertebrate Development

Compromised heat shock protein 90 (Hsp90) function reveals cryptic phenotypes in flies and plants. These observations were interpreted to suggest that this molecular stress-response chaperone has a capacity to buffer underlying genetic variation. Conversely, the protective role of Hsp90 could account for the variable penetrance or severity of some heritable developmental malformations in vertebrates. Using zebrafish as a model, we defined Hsp90 inhibitor levels that did not induce a heat shock response or perturb phenotype in wild-type strains. Under these conditions the severity of the recessive eye phenotype in sunrise, caused by a pax6b mutation, was increased, while in dreumes, caused by a sufu mutation, it was decreased. In another strain, a previously unobserved spectrum of severe structural eye malformations, reminiscent of anophthalmia, microphthalmia, and nanophthalmia complex in humans, was uncovered by this limited inhibition of Hsp90 function. Inbreeding of offspring from selected unaffected carrier parents led to significantly elevated malformation frequencies and revealed the oligogenic nature of this phenotype. Unlike in Drosophila, Hsp90 inhibition can decrease developmental stability in zebrafish, as indicated by increased asymmetric presentation of anophthalmia, microphthalmia, and nanophthalmia and sunrise phenotypes. Analysis of the sunrise pax6b mutation suggests a molecular mechanism for the buffering of mutations by Hsp90. The zebrafish studies imply that mild perturbation of Hsp90 function at critical developmental stages may underpin the variable penetrance and expressivity of many developmental anomalies where the interaction between genotype and environment plays a major role

3-D Photoionization Structure and Distances of Planetary Nebulae II. Menzel 1

We present the results of a spatio-kinematic study of the planetary nebula Menzel 1 using spectro-photometric mapping and a 3-D photoionization code. We create several 2-D emission line images from our long-slit spectra, and use these to derive the line fluxes for 15 lines, the Halpha/Hbeta extinction map, and the [SII] line ratio density map of the nebula. We use our photoionization code constrained by these data to derive the three-dimensional nebular structure and ionizing star parameters of Menzel 1 by simultaneously fitting the integrated line intensities, the density map, and the observed morphologies in several lines, as well as the velocity structure. Using theoretical evolutionary tracks of intermediate and low mass stars, we derive a mass for the central star of 0.63+-0.05 Msolar. We also derive a distance of 1050+_150 pc to Menzel 1.Comment: To be published in ApJ of 10th February 2005. 12 figure

Bacterial genomics reveal the complex epidemiology of an emerging pathogen in Arctic and boreal ungulates

Northern ecosystems are currently experiencing unprecedented ecological change, largely driven by a rapidly changing climate. Pathogen range expansion, and emergence and altered patterns of infectious disease, are increasingly reported in wildlife at high latitudes. Understanding the causes and consequences of shifting pathogen diversity and host-pathogen interactions in these ecosystems is important for wildlife conservation, and for indigenous populations that depend on wildlife. Among the key questions are whether disease events are associated with endemic or recently introduced pathogens, and whether emerging strains are spreading throughout the region. In this study, we used a phylogenomic approach to address these questions of pathogen endemicity and spread for Erysipelothrix rhusiopathiae, an opportunistic multi-host bacterial pathogen associated with recent mortalities in arctic and boreal ungulate populations in North America. We isolated E. rhusiopathiae from carcasses associated with large-scale die-offs of muskoxen in the Canadian Arctic Archipelago, and from contemporaneous mortality events and/or population declines among muskoxen in northwestern Alaska and caribou and moose in western Canada. Bacterial genomic diversity differed markedly among these locations; minimal divergence was present among isolates from muskoxen in the Canadian Arctic, while in caribou and moose populations, strains from highly divergent clades were isolated from the same location, or even from within a single carcass. These results indicate that mortalities among northern ungulates are not associated with a single emerging strain of E. rhusiopathiae, and that alternate hypotheses need to be explored. Our study illustrates the value and limitations of bacterial genomic data for discriminating between ecological hypotheses of disease emergence, and highlights the importance of studying emerging pathogens within the broader context of environmental and host factors

Körperproportionen der Leistungsstärkstenjuniorenruderer im bezug auf Wettkampfniveau,den Stil des Ruderns und die Bootsgattung

The performance of elite rowers is, beside others, determined by their physical characteristics. Anthropometric data for adult rowers emphasise the importance of body mass and body size for rowing performance. Little is known concerning the importance of proportional length development. At the 1997 World Junior Rowing Championships anthropometric measurements (body mass and 6 length dimensions) were performed on 383 elite male junior rowers. Based on these measurements several proportional length dimensions were calculated. Data on boat type were obtained by questionnaire and data on competition level were based on the results obtained during the championship. The results indicate that these rowers were heavier (Mean = 82.2±7.4 kg) and taller (Mean = 187.4±5.8 cm) and had a larger sitting height (Mean=96.8±3.2 cm) and longer legs (Mean= 90.7±3.8 cm) than a reference population. Finalists had significantly larger length dimensions than non-finalists and sweep rowers had in general larger length dimensions than scullers. No differences existed when the length dimensions were expressed proportional to the stature of the rowers. It can be concluded that elite junior rowers have larger length dimensions compared to less successful rowers, but these top athletes do not differentiate from the sub-elite athletes regarding proportional length development. Differences could be observed between sweep rowers and scullers with larger length dimensions in favour of sweep rowers.Uvod Natjecateljska uspješnost vrhunskih veslača određena je, između ostaloga, i njihovim tjelesnim karakteristikama. S biološkog stajališta možemo kod sportaša olimpijske i svjetske razine kvalitete očekivati optimalnu ekspresiju utjecaja nasljeđa, sportske pripreme, prehrane i socio-kulturnih faktora. Ispitivanje obilježja tih sportaša može pomoći kineziolozima, znanstvenicima i trenerima, u razumijevanju vrhunskog sportskog uspjeha time što im pruža informacije korisne za oblikovanje strategija za objašnjenje i predviđanje sportskih rezultata. U prošlosti su se antropometrijske studije bavile uglavnom veslačima seniorima, a manje juniorima. Te antropometrijske studije naglašavaju važnost tjelesne mase i veličine tijela za uspješnost u veslanju. Smatra se da osobitu prednost veslačima donose duži udovi zbog toga što su to duže poluge i što omogućuju veću radnu snagu. Duge noge pojačavaju potisnu fazu (provlak) veslačkog zaveslaja. Štoviše, veći veslači imaju veći presjek mišića i veći apsolutni energetski kapacitet. Proučavanje longitudinalnih dimenzija do sada je bilo uglavnom ograničeno na varijablu “visina tijela ili stas”. Samo je nekoliko studija o proporcijama longitudinalnih dimenzija vrhunskih veslača, pa se malo zna o važnosti longitudinalnih proporcija tijela veslača. Cilj je ove studije bio trostruk: (1) opisati razvojne proporcijske longitudinalne dimenzije juniora veslača u usporedbi s flamanskim mladićima, (2) usporediti tjelesne proporcije veslača prema različitim kvalitetnim natjecateljskim razinama, načinu veslanja i kategorijama čamca i (3) ustanoviti model antropometrijskog profila za veslače juniore. Metode Uzorak ispitanika činila su 383 veslača juniora, u dobi od 17,8 ± 0,7 godina, raspon godina od 15,1 do 18,6. Ispitanici su nastupili na FISA svjetskom ju-niorskom veslačkom prvenstvu 1997 godine. Istraživanjem je obuhvaćeno 90% sudionika (bez kormilara), od toga 83% pobjednika i osvajača meda-lja te 89% finalista. Svi su trenirali 7-10 puta tjedno (10-15 sati). Potpuni opis uzorka i mjerenja može se naći u članku Bourgois i suradnici (1998). Za ovaj članak upotrijebljene su sljedeće tjelesne dimenzije: tjelesna visina, sjedeća visina, duljina nadlaktice, duljina podlaktice, duljina šake i duljina potkoljenice. Mjerenja su provedena u standardnim uvjetima prema postupcima koje su opisali Claessens i suradnici (1998). Na temelju tih mjera izračunate su proporcijske longitudinalne dimenzije. Pregled varijabli prikazan je u tablici 1. Podaci o vrsti čamca prikupljeni su upitnikom, a podaci o kvalitetnoj razini temeljili su se na rezultatima postignutima na prvenstvu. Međunarodna juniorska veslačka natjecanja standardizirana su na stazi od 2 000 m i podijeljena su u discipline veslanja jednim veslom (rimen) i veslanja na pariće (skul). Te se veslačke tehnike međusobno dosta razlikuju – veslač u čamcu rimen, dakle, vesla samo jednim veslom, dok skuleri koriste dva kraća vesla koja povlače istodobno. Izračunati su parametri deskriptivne statistike (aritmetička sredina, standardna devijacija i raspon) za sve varijable i za ukupni uzorak veslača. Za usporedbu proporcijskih odnosa između rimen veslača i skul veslača te finalista i onih koji se nisu plasirali u finale upotrijebljen je Studentov t-test za nezavisne uzorke. Analiza varijance (ANOVA) i post-hoc Tukeyjev test primijenjeni su da bi se otkrile razlike u proporcionalnosti među veslačima u raznim vrstama čamaca. Za statističke analize korišten je računalni program Statistical Analysis System. Svi su testovi bili dvostruki, a značajnom se smatrala razlika na razini od p<0.05. Rezultati Deskriptivna statistika prikazana je u tablici 3. U tablici su uspoređene proporcije veslača u rimenu i skulu. Rimen veslači bili su značajno viši i teži od skulera. Kada su se longitudinalne dimenzije dovele u proporcijski odnos prema tjelesnoj visini, nisu primijećene značajne razlike između te dvije vrste veslača. Slični su se rezultati dobili i u usporedbi finalista i ne-finalista (tablica 5). Prema rezultatima analize varijance (tablica 6) razlike između dva stila veslanja (rimen nasuprot skul) nađene su između dvojca sa (2+) i četverca sa (4+), s jedne strane, te samca (1x), četverca na pariće (4x) i dvojca bez (2-), s druge strane. Sportaši koji veslaju u dvojcu sa (2+) i četvercu sa (4+) bili su, u prosjeku, teži i viši od veslača u samcu (1x), četvercu na pariće (4x) i dvojcu bez (2-). Nisu dobivene razlike u proporcijskim odnosima longitudinalnih dimenzija prema vrsti čamaca. U tablici 7 predstavljen je model profila proporcijskih odnosa longitudinalnih dimenzija za veslače juniore koji su nastupili na FISA svjetskom juniorskom veslačkom prvenstvu. Rasprava i zaključak Rezultati pokazuju da su promatrani veslači teži i viši te da imaju veću sjedeću visinu i duže noge od opće populacije. Finalisti su imali značajno veće longitudinalne dimenzije od ne-finalista, a rimen veslači su općenito imali veće longitudinalne dimenzije od skulera. Nisu, međutim, dobivene razlike kada su longitudinalne dimenzije postavljene u proporcijski odnos prema tjelesnoj visini. Veslanje je sport izdržljivosti i longitudinalne dimenzije su nedvojbeno povezane s uspješnošću. Duge noge pojačavaju potisak u fazi provlaka tijekom veslačkog zaveslaja, što znači da su veslači s dugim nogama u biomehaničkoj prednosti. Usporedba tjelesnih proporcija izmjerenih veslača juniora s vrijednostima o kojima su izvijestili drugi autori (Carter i dr., 1982; Rodriguez, 1986) otkriva da veslači juniori imaju manju sjedeću visinu u odnosu na ukupnu tjelesnu visinu ili stas (Valoisov indeks) (51,6%) i veću duljinu nogu u odnosu na stas (48,4%) od normativne usporedne skupine (Ostyn i dr., 1980) (52,1% i 47,9%) i od teških olimpijskih veslača (Carter i dr, 1982) (52,1% i 47,.9%). Nisu dobivene razlike između veslača juniora i vrhunskih lakih veslača (51,5% i 48,5%). Može se zaključiti da su kvalitetniji veslači uglavnom viši i, povezano s tom razlikom, imaju veće longitudinalne dimenzije od manje uspješnih veslača, ali se oni ne razlikuju međusobno kada se te vrijednosti izraze proporcionalno u odnosu na njihovu tjelesnu visinu. Uočene su razlike između rimen veslača i skul veslača – rimen veslači su višega stasa i imaju veće apsolutne vrijednosti longitudinalnih dimenzija. Uz to što je izrađen profil veslača juniora, rezultati ove studije mogu pomoći trenerima i kineziolozima da steknu bolji uvid u to koje su morfološke karakteristike povezane s uspješnošću u veslanju. Rezultati se također mogu primijeniti za određenje antropometrijskog profila veslača i kao instrument za selekciju dječaka talentiranih za veslanje.Die Leistung der leistungsstärksten Ruderer ist unter anderem von ihren körperlichen Eigenschaften bestimmt. Körperbaudaten für erwachsene Ruderer stellen den Nachdruck auf die Wichtigkeit des Körpergewichts und der Körperhöhe für das Rudern. Es bleibt noch unklar, wie wichtig die proportionale Längenzunahme ist. Während der Junioren Weltmeisterschaften im 1997 wurden die Körperbau-Messungen (Körpergewicht und 6 Extremitätenlängen) auf 383 leistungsstärksten Junioren-Ruderer vorgenommen. Auf Grund dieser Messungen einige proportionale Extremitätenlängen wurden berechnet. Die Angaben über die Bootsgat-tung wurden einem Fragebogen entnommen, während die Angaben über dem Wettkampf-Niveau auf den während der Meisterschaft gewonnenen Ergebnissen basierten. Den Ergebnissen nach wogen diese Ruderer mehr (Mittelwert = 82,2±7,4 kg), sie waren größer (Mittelwert = 187,4±5,8 cm) und hatten eine größere Sitzhöhe (Mittelwert = 96,8±3,2 cm) und längere Beine (Mittelwert = 90,7±3,8 cm) als die Referenz-Grundgesamtheit. Die Finalisten hatten bedeutend größere Extremitätenlängenwerte als die Nicht-Finalisten, während die Riemenruderer im allgemeinen größere Extremitätenlängenwerte hatten als die Skuller. Keine Unterschiede waren zu merken, wenn die Extremitätenlängenwerte proportional der Körperhöhe der Ruderer dargestellt wurden. Daraus lässt sich schließen, dass die leistungsstärksten Junioren größere Extremitätenlängenwerte haben im Vergleich zu den weniger erfolgreichen Ruderern, aber diese Spitzensportler unterscheiden sich keineswegs von weniger erfolgreichen Sportlern im Bezug auf die proportionale Längenzunahme. Die Unterschiede sind bei den Riemenruderern und den Skullern zu merken, wobei die Skuller größere Extremitätenlängenwerte aufzeigen