Relationship between fire,climate oscillations,and drought in British Columbia,Canada, 1920–2000

Climate oscillations such as El Niño–Southern Oscillation (ENSO) and Pacific Decadal Oscillation (PDO) are known to affect temperature and precipitation regimes and fire in different regions of the world. Understanding the relationships between climate oscillations, drought, and area burned in the past is required for anticipating potential impacts of regional climate change and for effective wildfire‐hazard management. These relationships have been investigated for British Columbia (BC), Canada, either as part of national studies with coarse spatial resolution or for single ecosystems. Because of BC's complex terrain and strong climatic gradients, an investigation with higher spatial resolution may allow for a spatially complete but differentiated picture. In this study, we analyzed the annual proportion burned–climate oscillation–drought relationships for the province's 16 Biogeoclimatic Ecosystem Classification (BEC) zones. Analyses are based on a digital, spatially explicit fire database, climate oscillation indices, and monthly precipitation and temperature data with a spatial resolution of 400 m for the period 1920–2000. Results show that (1) fire variability is better related to summer drought than to climate oscillations, and that (2) fire variability is most strongly related to both, climate oscillations and summer drought in southeastern BC. The relationship of area burned and summer drought is strong for lower elevations in western BC as well. The influence of climate oscillations on drought is strongest and most extensive in winter and spring, with higher indices being related to drier conditions. Winter and spring PDO and additive winter and spring PDO+ENSO indices show BC's most extensive significant relationship to fire variability. Western BC is too wet to show a moisture deficit in summer that would increase annual area burned due to teleconnections.     

The Devonian nekton revolution

Klug, C., Kröger, B., Kiessling, W., Mullins, G.L., Servais, T., Frýda, J., Korn, D. & Turner, S. 2009: The Devonian nekton revolution. Lethaia, 10.1111/j.1502‐3931.2009.00206.x Traditional analyses of Early Phanerozoic marine diversity at the genus level show an explosive radiation of marine life until the Late Ordovician, followed by a phase of erratic decline continuing until the end of the Palaeozoic, whereas a more recent analysis extends the duration of this early radiation into the Devonian. This catch‐all approach hides an evolutionary and ecological key event long after the Ordovician radiation: the rapid occupation of the free water column by animals during the Devonian. Here, we explore the timing of the occupation of the water column in the Palaeozoic and test the hypothesis that ecological escalation led to fundamental evolutionary changes in the mid‐Palaeozoic marine water column. According to our analyses, demersal and nektonic modes of life were probably initially driven by competition in the diversity‐saturated benthic habitats together with the availability of abundant planktonic food. Escalatory feedback then promoted the rapid rise of nekton in the Devonian as suggested by the sequence and tempo of water‐column occupation. □Devonian, diversity, ecology, food webs, nekton, plankton, radiation.     

Extensive intraspecific variation in a Triassic ammonoid from Siberia

The ammonoid species Czekanowskites rieberin.sp . from the Lower Anisian of Arctic Siberia (River Olenek) shows an enormous range of intraspecific variability. The 700 investigated specimens are packed in one single concretion. They are all adult with preserved living chambers and apertural structures. Morphologically they range from keeled smooth suboxycones with narrow umbilicus, through feebly ribbed platycones with a little wider umbilicus, to subcadicones with relatively wide umbilicus and straight ribs with bullae. The morphological variation is continuous; all specimmh belong to a single genetically linked population, variants of one biospecies. This phenomenon, which is quite common in boreal Triassic ammonoid faunas, has in the past led to serious taxonomic oversplitting. It presents a serious challenge to current ideas about a close correlation between modeof life and shell morphology in arnmonoids.□ Amntonoidea, boreal Triassic, ecology. Siberia, variability .     

Oral Fertilization in a Mouthbrooding Cichlid Fish

It has been hypothesized that in maternal mouthbrooding cichlids the conspicuous markings on the male's anal fin function as “egg-dummies” by fooling the female into snapping at them, thereby inhaling sperm and assuring fertilization of the eggs in the mouth. I show experimentally in Pseudocrenilabrus multicolor, an East African maternal mouthbrooder, that indeed oral fertilization takes place. Nevertheless, external fertilization plays a significant role, too.     

The daily pattern of autumn bird migration in the northern Sahara

The temporal pattern of migration by passerine birds during the night, and their arrival during the day at the Egyptian coast and in the northern Sahara Desert was investigated. The mean direction of nocturnal migration at the coast was south-southeast, while at all desert sites it was south-southwest.
Birds arrived at the Egyptian coast only during the second half of the night which is explained by the fact that no birds could have taken off from the Mediterranean Sea. At least some of the birds landed at the coast where they spent the day before taking off shortly after sunset. These birds passed the desert sites at the expected time of day assuming a ground speed of 18 m per second. However, the origin of the birds passing the desert sites early at night is unclear. They must either have spent the day in the desert north of the study sites or they had overflown the Egyptian coast in the afternoon without landing.
The landing of birds during the day at the desert sites was bimodal. This pattern of arrival is explained either by some birds having landed at the Egyptian coast in the early morning before continuing, or by deteriorating conditions later in the day during flight or when resting in the desert, that obliged them to seek shelter at the desert sites.
A correlation between the number of migrants observed during the night and the number of resting birds in the desert on the following day suggests that an unknown proportion of birds might regularly use an intermittent migratory strategy that includes rest periods by day when crossing the desert, whereas others might adapt a non-stop migratory strategy.     

The GIRK1 Brain Variant GIRK1d and Its Functional Impact on Heteromultimeric GIRK Channels

Four isoforms of GIRK channels (GIRK1–4) have been described in humans. In addition, several splice variants of more or less unknown function have been identified from several tissues and species. In our study, we investigated the structure and function of a new variant of GIRK1 that has been isolated from rat brain. Because of wide similarities with a previously described variant, we also named it GIRK1d. This variant lacks a region corresponding to exon 2 of full-length GIRK1, leading to a truncated GIRK1 that lacks the main part of the C-terminus. To study GIRK1d we used the Xenopus laevis expression system, the two-electrode voltage clamp method, and confocal laser scan microscopy. We found that our GIRK1d variant preferentially binds GIRK2 or GIRK4 over GIRK1. Furthermore, it largely reduces conductances mediated by GIRK1/2 or GIRK1/4 hetero-multimeric channels when coexpressed and nearly totally abolishes currents when replacing GIRK1 in hetero-multimeric channels.     

Properties of Purified L-Ornithine Decarboxylase (EC 4.1.1.17) from Tetrahymena thermophila

Ornithine decarboxylase (ornithine carboxy lyase; EC 4.1.1.17) (ODC) from Tetrahymena thermophila was purified 6,300 fold employing fractionated ammonium sulfate precipitation, gel permeation chromatography on Sephadex G-150, ion exchange chromatography on DEAE-Sepharose CL-6B, and preparative isoelectric focussing. The product obtained in 24% yield was a preparation of the specific activity of 10,200 nmol CO₂mdh^-1mdmg^-1. The purified enzyme was rather stable at 37°C (14% loss of activity within 1 h). The molecular and catalytic properties of this enzyme were investigated. The isoelectric point was 5.7 and the molecular weight (MW) was estimated to be 68,000 under nondenaturing conditions. The pH optimum was between 6.0 and 7.0, the K_m for the substrate L-ornithine was 0.11 mM, and the K_m for the cofactor pyridoxal 5-phosphate was 0.12 μM; the product of ODC catalysis, putrescine, was a poor inhibitor with an estimated K_i of about 10 mM. The enzyme was inhibited competitively by D-ornithine with a K_i of 1.6 mM and by α-difluoromethylornithine with a K_i of 0.15 mM. The latter one, an enzyme activated irreversible inhibitor of mammalian ODC, inactivated the enzyme from T. thermophila at high concentrations with a half life time of 14 min. Other basic amino acids, e.g. L-lysine, L-arginine, and L-histidine, were neither substrates nor inhibitors of the enzyme, as were the diamines 1,3-diaminopropanol and cadaverine, the polyamines spermidine and spermine and the cosubstrate analogues pyridoxal and pyridoxamine-5-phosphate. Polyanions were activators of the enzyme: The half maximal ODC stimulating concentrations were 2.2 μgmdml^-1 for RNA, 6.1 μgmdml^-1 for DNA, and 0.25 μgmdml^-1 for heparin. These results indicate that ODC from T. thermophila shares several properties with ODC preparations from other organisms but in some respects, especially in activator and inhibitor specificity, there are some special qualities unique to this particular protozoan enzyme.