Processes of sustentation and collapse of algal aggregations of the Marimo (Aegagropila linnaei) in Lake Akan, Japan, and Lake Mývatn, Iceland

第3回極域科学シンポジウム/第34回極域生物シンポジウム 11月27日（火） 国立極地研究所 ３階ラウン

Midge-stabilized sediment drives the composition of benthic cladoceran communities in Lake Mývatn, Iceland

The importance of environmental disturbances as drivers of ecological communities depends not only on the magnitude of the disturbance, but also on the disturbance-specific sensitivity of the community. Organisms that alter the physical structure of their surroundings can affect the sensitivity of their habitat to environmental disturbance, and may alter the potential for disturbance to shape ecological communities. Such organisms therefore act as ecosystem engineers by indirectly modifying the resources available to other species. The benthos of shallow, eutrophic Lake Mývatn, Iceland, is frequently disturbed by wind events that lead to sediment resuspension. The impact of wind, however, depends on the abundance of midges (Chironomidae) whose larval tubes bind sediment and reduce wind-driven resuspension. Here, we investigate the long-term effect of fluctuations in midge abundance on the benthic cladoceran community using two lake sediment cores representing 30 and 140 years of deposition. In both cores, midge remains show a significant positive correlation with abundance of a large benthic surface-dwelling cladoceran, Eurycercus lamellatus, relative to the abundance of a small within-sediment-dwelling cladoceran, Alona rectangula. To experimentally investigate whether this shift could have been caused by midges acting as ecosystem engineers, we subjected cladoceran communities to sediment resuspension events within mesocosms. We found a significant decrease in abundance of the large epibenthic E. lamellatus relative to the abundance of small infaunal Alona spp. when subjected to disturbance. These findings show that physical alteration of benthic sediment and hence the sensitivity of the sediment to disturbance may explain the community shift in cladocerans observed with fluctuating midge abundance in Lake Mývatn.National Science Foundation Graduate Research Fellowship. Grant Number: DGE-1256259 LTREB. Grant Number: DEB-1052160Peer Reviewe

Rare variants with large effects provide functional insights into the pathology of migraine subtypes, with and without aura

Publisher Copyright: © 2023, The Author(s).Migraine is a complex neurovascular disease with a range of severity and symptoms, yet mostly studied as one phenotype in genome-wide association studies (GWAS). Here we combine large GWAS datasets from six European populations to study the main migraine subtypes, migraine with aura (MA) and migraine without aura (MO). We identified four new MA-associated variants (in PRRT2, PALMD, ABO and LRRK2) and classified 13 MO-associated variants. Rare variants with large effects highlight three genes. A rare frameshift variant in brain-expressed PRRT2 confers large risk of MA and epilepsy, but not MO. A burden test of rare loss-of-function variants in SCN11A, encoding a neuron-expressed sodium channel with a key role in pain sensation, shows strong protection against migraine. Finally, a rare variant with cis-regulatory effects on KCNK5 confers large protection against migraine and brain aneurysms. Our findings offer new insights with therapeutic potential into the complex biology of migraine and its subtypes.Peer reviewe

Það sem hentar skólanum best. Útfærsla á vinnutíma grunnskólakennara samkvæmt bókun 5 og ákvæði 2.1.6.3

Í kjarasamningum milli sveitarfélaga og Félags grunnskólakennara sem gerðir voru 2001 var sett inn bókun sem gerði það mögulegt að skólar gætu tekið upp breytt vinnutímafyrirkomulag frá því sem almennt gerist í grunnskólum hér á landi. Í þessari rannsókn var markmiðið að skoða reynslu þeirra sem starfað hafa í grunnskólum sem tekið hafa upp vinnutímafyrirkomulag samkvæmt bókun 5 og síðar grein 2.1.6.3 í kjarasamningi grunnskólakennara. Í rannsókninni er notuð blönduð rannsóknaraðferð. Í eigindlega hluta rannsóknarinnar þar sem tekin voru hálfopin viðtöl var spurt hver reynsla stjórnenda í skólum sem útfæra vinnutíma grunnskólakennara samkvæmt ákvæði 2.1.6.3 (bókun 5) væri. Í megindlega hluta rannsóknarinnar var lagður spurningalisti fyrir kennara þessara sömu skóla. Annars vegar var spurt um hvaða áhrif vinnufyrirkomulagið hefði á innra starf skólans og hins vegar um viðhorf kennara skólanna til vinnufyrirkomulagsins. Helstu niðurstöður eru þær að stjórnendur telja þetta fyrirkomulag hafa ótvíræðan ávinning í för með sér fyrir alla hagsmunaaðila sem koma að skólastarfinu. Þeir eru sammála um að þessi útfærsla á vinnutíma kennara stuðli að betra skólastarfi. Í spurningakönnun sem lögð var fyrir kennara skólanna kom fram að þeir eru sáttir við að vinna eftir þessu vinnutímafyrirkomulagi og telja að það hafi jákvæð áhrif á innra starf skólanna sem skili sér í betra skólastarfi. Þeir skólar sem farið hafa út í að vinna samkvæmt breyttu vinnutímafyrirkomulagi hafa þurft að yfirstíga ýmsar hindranir ekki síst vegna andstöðu Félags grunnskólakennara við að þessi leið sé farin

Umbrotin við Kröflu 1975-89

Peer reviewe

Age of the Younger Laxá Lava and Lake Mývatn, Northern Iceland, Determined by AMS Radiocarbon Dating

Lake Mývatn and several smaller lakes in northern Iceland were formed by the large Holocene lava flow of the Younger Laxá Lava (YLL). The age of the YLL was estimated by tephrochronology at 1800–2300 BP (Thorarinsson 1951). Conventional radiocarbon dating of charred vegetation beneath the YLL (Thorarinsson 1964) yielded uncalibrated ages of 1940 ± 270 14C yr BP (Yale), 2110 ± 140 14C yr BP (Copenhagen), and 1990 ± 50 14C yr BP (Winnipeg). Ongoing paleolimnological research at Lake Mývatn requires a more precise age estimation of the YLL. Charcoal samples from beneath the YLL was collected at Presthvammur in 2007 and analyzed by accelerator mass spectrometry (AMS) 14C measurements. The reliability of the conventional 14C ages of the samples Yale, Copenhagen, and Winnipeg was re-evaluated, applying criteria from Pettit et al. (2003) and Graf (2009). The result of AMS 14C measurement (2170 ± 38 cal yr BP) underpins the local tephrochronology and provides a reliable age of the YLL and Lake Mývatn.The Radiocarbon archives are made available by Radiocarbon and the University of Arizona Libraries. Contact [email protected] for further information.Migrated from OJS platform February 202

Johnny Briscoe (right) with rifle and unidentified person shooting camels at Maryvale Station (now Titjikala) 100km south east of Alice Springs, Northern Territory 1957 [picture].

Title from acquisition documentation, see file NLA 07/1572.; Acquired in digital format; access copy available online.; Part of the collection: Aspects of Aboriginal mission life.; "Too many camels breeding up"--Acquisition documentation.; Mode of access: Internet via World Wide Web

Spatial phenotypic and genetic structure of threespine stickleback (Gasterosteus aculeatus) in a heterogeneous natural system, Lake Mývatn, Iceland

Eco‐evolutionary responses of natural populations to spatial environmental variation strongly depend on the relative strength of environmental differences/natural selection and dispersal/gene flow. In absence of geographic barriers, as often is the case in lake ecosystems, gene flow is expected to constrain adaptive divergence between environments – favoring phenotypic plasticity or high trait variability. However, if divergent natural selection is sufficiently strong, adaptive divergence can occur in face of gene flow. The extent of divergence is most often studied between two contrasting environments, whereas potential for multimodal divergence is little explored. We investigated phenotypic (body size, defensive structures, and feeding morphology) and genetic (microsatellites) structure in threespine stickleback (Gasterosteus aculeatus) across five habitat types and two basins (North and South) within the geologically young and highly heterogeneous Lake Mývatn, North East Iceland. We found that (1) North basin stickleback were, on average, larger and had relatively longer spines than South basin stickleback, whereas (2) feeding morphology (gill raker number and gill raker gap width) differed among three of five habitat types, and (3) there was only subtle genetic differentiation across the lake. Overall, our results indicate predator and prey mediated phenotypic divergence across multiple habitats in the lake, in face of gene flow.ISSN:2045-775