Vertical zonation of testate amoebae in the Elatia Mires, northern Greece : palaeoecological evidence for a wetland response to recent climate change or autogenic processes?

The Elatia Mires of northern Greece are unique ecosystems of high conservation value. The mires are climatically marginal and may be sensitive to changing hydroclimate, while northern Greece has experienced a significant increase in aridity since the late twentieth century. To investigate the impact of recent climatic change on the hydrology of the mires, the palaeoecological record was investigated from three near-surface monoliths extracted from two sites. Testate amoebae were analysed as sensitive indicators of hydrology. Results were interpreted using transfer function models to provide quantitative reconstructions of changing water table depth and pH. AMS radiocarbon dates and 210Pb suggest the peats were deposited within the last c. 50 years, but do not allow a secure chronology to be established. Results from all three profiles show a distinct shift towards a more xerophilic community particularly noted by increases in Euglypha species. Transfer function results infer a distinct lowering of water tables in this period. A hydrological response to recent climate change is a tenable hypothesis to explain this change; however other possible explanations include selective test decay, vertical zonation of living amoebae, ombrotrophication and local hydrological change. It is suggested that a peatland response to climatic change is the most probable hypothesis, showing the sensitivity of marginal peatlands to recent climatic change

Methanobactin and the Link Between Copper and Bacterial Methane Oxidation

Methanobactins (mbs) are low-molecular-mass (<1,200 Da) copper-binding peptides, or chalkophores, produced by many methane-oxidizing bacteria (methanotrophs). These molecules exhibit similarities to certain iron-binding siderophores but are expressed and secreted in response to copper limitation. Structurally, mbs are characterized by a pair of heterocyclic rings with associated thioamide groups that form the copper coordination site. One of the rings is always an oxazolone and the second ring an oxazolone, an imidazolone, or a pyrazinedione moiety. The mb molecule originates from a peptide precursor that undergoes a series of posttranslational modifications, including (i) ring formation, (ii) cleavage of a leader peptide sequence, and (iii) in some cases, addition of a sulfate group. Functionally, mbs represent the extracellular component of a copper acquisition system. Consistent with this role in copper acquisition, mbs have a high affinity for copper ions. Following binding, mbs rapidly reduce Cu2+ to Cu1+. In addition to binding copper, mbs will bind most transition metals and near-transition metals and protect the host methanotroph as well as other bacteria from toxic metals. Several other physiological functions have been assigned to mbs, based primarily on their redox and metal-binding properties. In this review, we examine the current state of knowledge of this novel type of metal-binding peptide. We also explore its potential applications, how mbs may alter the bioavailability of multiple metals, and the many roles mbs may play in the physiology of methanotrophs

A distinct role for B1b lymphocytes in T cell-independent immunity

Pathogenesis of infectious disease is not only determined by the virulence of the microbe but also by the immune status of the host. Vaccination is the most effective means to control infectious diseases. A hallmark of the adaptive immune system is the generation of B cell memory, which provides a long-lasting protective antibody response that is central to the concept of vaccination. Recent studies revealed a distinct function for B1b lymphocytes, a minor subset of mature B cells that closely resembles that of memory B cells in a number of aspects. In contrast to the development of conventional B cell memory, which requires the formation of germinal centers and T cells, the development of B1b cell-mediated long-lasting antibody responses occurs independent of T cell help. T cell-independent (TI) antigens are important virulence factors expressed by a number of bacterial pathogens, including those associated with biological threats. TI antigens cannot be processed and presented to T cells and therefore are known to possess restricted T cell-dependent (TD) immunogenicity. Nevertheless, specific recognition of TI antigens by B1b cells and the highly protective antibody responses mounted by them clearly indicate a crucial role for this subset of B cells. Understanding the mechanisms of long-term immunity conferred by B1b cells may lead to improved vaccine efficacy for a variety of TI antigens

The potential to encode sex, age, and individual identity in the alarm calls of three species of Marmotinae

In addition to encoding referential information and information about the sender’s motivation, mammalian alarm calls may encode information about other attributes of the sender, providing the potential for recognition among kin, mates, and neighbors. Here, we examined 96 speckled ground squirrels (Spermophilus suslicus), 100 yellow ground squirrels (Spermophilus fulvus) and 85 yellow-bellied marmots (Marmota flaviventris) to determine whether their alarm calls differed between species in their ability to encode information about the caller’s sex, age, and identity. Alarm calls were elicited by approaching individually identified animals in live-traps. We assume this experimental design modeled a naturally occurring predatory event, when receivers should acquire information about attributes of a caller from a single bout of alarm calls. In each species, variation that allows identification of the caller’s identity was greater than variation allowing identification of age or sex. We discuss these results in relation to each species’ biology and sociality

Fe₃O₄ activities in Fe-Ti spinel solid solutions

Environmental philosophy is a promising branch of philosophy to renew the ancient tradition of philosophy as a way of life. I contend that to practice philosophy as a way of life involves both some conception of the good life and an array of spiritual exercises that assists one in living according to that conception. I then offer an argument for why this tradition of philosophy is worth reviving at the present time. The second half of the paper is devoted to exploring the prospects for a distinctively environmental approach to philosophy as a way of life. Give its emphasis on environmental virtue and its rich resources for developing spiritual exercises, I argue that environmental philosophy as a way of life is both a robust and attractive option

Oxygen thermobarometry of orogenic lherzolite massifs

The oxidation state has been determined for spinel peridotites from 13 orogenic lherzolite massifs including Beni Bousera, Ronda, and 11 smaller massifs in the French Pyrenees. The oxygen fugacity (f o2) was calculated for 67 samples from microprobe analyses using a set of secondary spinel standards to correct the ferric iron content in the spinels. The utility of this method is confirmed by the good agreement between the calculated values and those determined by Mossbauer spectroscopy on 28 samples.The spinel peridotites of Ronda and Beni Bousera are relatively reduced, averaging -11 and -1.5 log units relative to fayalite-magnetite-quartz (FMQ) respectively, which is in agreement with values from abyssal peridotites and mid-ocean ridge basalt (MORB) glasses. The Pyrenean massifs are relatively oxidized [ΔlogfO2(FMQ)=-0.4] and are intermediate between the abyssal peridotites and continental xenolith suites. No systematic gradients are observable. Instead, variations of up to 2 log units in f o2 occur at a localized scale. This type of variation is also observed for trace elements and radiogenic isotopes. The harzburgites at Beni Bousera record the most reduced conditions. Local oxidation coincides with the appearance of amphibolc, indicating that metasomatizing fluids or melts are generally oxidized compared with the host peridotites. Partial re-equilibration in the plagioclase peridotite fades has occurred at Ronda, causing the spinels to become Cr rich. Re-equilibration is extremely heterogeneous. Mild oxidation appears to attend the crystallization of fine-grained plagioclase.The similarity in fo 2 values at Beni Bousera and Ronda indicates a fairly uniform oxidation state at a scale of ̃ 200 km. This scale of homogeneity is also observed in the Pyrenees, where no significant variation in f o2 is apparent along 200 km of strike in the Northern Pyrenean Zone. © 1992 Oxford University Press