Binding of SH2 domains of phospholipase C gamma 1, GAP, and Src to activated growth factor receptors

Phospholipase C gamma 1 (PLC gamma 1) and p21ras guanosine triphosphatase (GTPase) activating protein (GAP) bind to and are phosphorylated by activated growth factor receptors. Both PLC gamma 1 and GAP contain two adjacent copies of the noncatalytic Src homology 2 (SH2) domain. The SH2 domains of PLC gamma 1 synthesized individually in bacteria formed high affinity complexes with the epidermal growth factor (EGF)- or platelet derived growth factor (PDGF)-receptors in cell lysates, and bound synergistically to activated receptors when expressed together as one bacterial protein. In vitro complex formation was dependent on prior growth factor stimulation and was competed by intracellular PLC gamma 1. Similar results were obtained for binding of GAP SH2 domains to the PDGF-receptor. The isolated SH2 domains of other signaling proteins, such as p60src and Crk, also bound activated PDGF-receptors in vitro. SH2 domains, therefore, provide a common mechanism by which enzymatically diverse regulatory proteins can physically associate with the same activated receptors and thereby couple growth factor stimulation to intracellular signal transduction pathways.     

Paleo-Eskimo mtDNA genome reveals matrilineal discontinuity in Greenland

The Paleo-Eskimo Saqqaq and Independence I cultures, documented from archaeological remains in Northern Canada and Greenland, represent the earliest human expansion into the New World's northern extremes. However, their origin and genetic relationship to later cultures are unknown. We sequenced a mitochondrial genome from a Paleo-Eskimo human by using 3400-to 4500-year-old frozen hair excavated from an early Greenlandic Saqqaq settlement. The sample is distinct from modern Native Americans and Neo-Eskimos, falling within haplogroup D2a1, a group previously observed among modern Aleuts and Siberian Sireniki Yuit. This result suggests that the earliest migrants into the New World's northern extremes derived from populations in the Bering Sea area and were not directly related to Native Americans or the later Neo-Eskimos that replaced them.     

Ethanol-induced apoptotic neurodegeneration and fetal alcohol syndrome

The deleterious effects of ethanol on the developing human brain are poorly understood. Here it is reported that ethanol, acting by a dual mechanism [blockade of N-methyl-D-aspartate (NMDA) glutamate receptors and excessive activation of GABA(A) receptors], triggers widespread apoptotic neurodegeneration in the developing rat forebrain. Vulnerability coincides with the period of synaptogenesis, which in humans extends from the sixth month of gestation to several years after birth. During this period, transient ethanol exposure can delete millions of neurons from the developing brain. This can explain the reduced brain mass and neurobehavioral disturbances associated with human fetal alcohol syndrome.     

Influence of land use in small karst watersheds on the chemical status of peloid sediments on the eastern Adriatic coast

Background, Aim and Scope  

Most of the cathment areas supplying water and mineral matter to the Adriatic bays with healing mud/peloids are affected by various degrees of human impact, i.e. activity that is introducing various types of contaminants to environment. The bays represent shallow marine depositional environments where organic-rich sediments accumulate. Investigations for balneological characterization of several localities along the Croatian coast have shown that these organic-rich sediments may be classified as healing mud, i.e. peloids. Healing mud due to its balneologic features is in treatment of various diseases and in improvement of the overall health conditions and general well-being. Various components of mud, particularly trace elements, could be absorbed through dermal contact. Therefore, the study of the abundance of such potentially toxic elements as As, Pb, Hg, Cd, Se, Sb, Cu, Zn in marine sediments used as healing mud is necessary in order to know their mobility and to avoid possible intoxications.     

Comparing the potential effectiveness of conservation planning approaches in central North Carolina, USA

We compared four approaches to conservation site selection to protect forest biodiversity in the Triangle Region of North Carolina, USA. Using biological inventory data and an inventory-based conservation plan as benchmarks, we evaluated the potential effectiveness of a focal species plan and three “simple” plans (large forested patches, close to wetlands and riparian areas, diverse forest types). Effectiveness was measured in three ways: the number of inventory elements captured at least once by the plan (representation), the total number of inventory elements captured (completeness), and the proportion of land in the inventory-based plan included (overlap). We further examined the potential effectiveness of the simple plans by calculating their overlap with land identified by the focal species approach. The simple and focal species plans did not differ markedly in terms of representation, but diverged when completeness and overlap were considered. Although representation rates for all four plans were relatively high, lower rates for completeness and overlap raise concerns about long-term viability. The simple plans did not identify the same lands as the focal species plan, and are thus unlikely to provide appropriate habitat for the focal species. Each approach we tested failed to capture some subset of species and communities, highlighting the importance of explicit conservation targets and consideration of ecological processes. Forced to act quickly and with little data, our findings suggest using initially a set of complementary simple plans, each focused on a different habitat type. This should be considered a stopgap measure, however, while more sophisticated plans are constructed, defining explicit conservation targets and considering ecological processes.     

Aufnahme und Verlagerung von 15N-Stickstoff bei Sommergerste in Abhängigkeit von K-Ernährung und Mehltaubefall

¹⁵N uptake and distribution by spring barley in relation to K nutrition and mildew attack Barley cv. Aramir was grown in complete nutrient solution containing 0,5 (K₁), 1,5 (K₂) and 4,5 mM K (K₃) respectively till maturity. Part of the plants was infected by mildew (Erysiphe graminis), whereas control treatments were kept mildew-free by fungicide sprays. Symptoms of mildew attack were less at K₂ and K₃ and grain yields of infected plants were raised from 98 (K₁) to 160 (K₂) and 165 g/pot (K₃). In control treatments grain yields were 130 (K₁), 164 (K₂) and 163 (K₃) g/pot. During anthesis nitrogen in the nutrient solution was labelled with ¹⁵N for two days and ¹⁵N metablism was studied within 7 consecutive days. The aim of this pulse-chase experiment was to find out, how mildew attack and K nutrition influence N metabolism. The following results were obtained: a) ¹⁵N uptake increased from K₁ to K₂ in infected and healthy plants, though at slightly lower levels in the infected treatments. b) During 7 days after the ¹⁵N pulse up to 17,1% of the ¹⁵N absorbed were translocated into the grains. Better K status as well as spray treatments stimulated nitrogen translocation. c) Mildew attack of leaves does not seem to influence the conversion of grain-¹⁵N into grain proteins. Better K supply stimulates the rate of protein synthesis in the grain. d) In mildew infected leaves relatively more of the ¹⁵N absorbed is incorporated into leaf proteins. But this may be a consequence of slower grain growth, because already 7 days after anthesis infected plants in all K treatments had significantly lower grain yield. In spite of the short duration of the experiment the ¹⁵N data do not indicate that the visible depression of mildew attack by better K nutrition of the crop might inter alia be due to K stimulated defense reactions within N metabolism. This is in agreement with a previous experiment.