Delayed oviposition: a female strategy to counter infanticide by males?

Conflicts of interest between males and females can lead toan evolutionary arms race in which adaptations of each sex coevolve.Intersexual conflict is extreme in the brood caring, semelparousspider Stegodyphus lineatus; males encountering females thathave already produced their usually single egg sac attempt toremove and discard the egg sac and then remate with the female. Femalesthat cannot defend their eggs lose valuable time and fecundityby having to replace the clutch. Selection should favor femalesthat complete their suicidal maternal care as quickly as possiblebecause of the high risk of predation. However, some femalestake up to four times longer to oviposit than others. I proposethat females minimize the risk of male infanticide by postponingoviposition. Accordingly, early-maturing females, who sufferthe highest risk of infanticide by males, should have a longerinterval between maturation and oviposition than late-maturingfemales. The date of maturation significantly predicted theinterval between maturation and oviposition and explained upto 35% of its variation in a data set from a natural population andlonger term data from a seminatural, enclosed population. Bodysize was predicted to have a weak effect on the timing of ovipositionand was consistently less important than maturation date. Theobserved facultative timing of oviposition may have evolvedas a result of intersexual conflict over mating.     

Life cycle assessment of passively aerated composting in gas-permeable bags of olive mill waste

The International Journal of Life Cycle Assessment - In Italy, composting olive mill waste has become a common practice, since it mitigates the environmental problems associated with spreading the...     

The mechanism of Mo-/Cu-dependent CO dehydrogenase

Density functional theory computations at the B3LYP/SDDp//B3LYP/Lanl2DZ level were performed on model complexes derived from [(Me₂C₂S₂)Mo(O)₂-S-CuSMe]²⁻ or its oxo protonated form to gain insight into the reaction steps involved in substrate oxidation of a Mo-/Cu-dependent CO dehydrogenase. Only the bisoxo but not the hydroxo oxo complex was found to oxidize CO exothermically. A thiocarbamate complex structurally characterized as the reaction product of the enzyme with the inhibitor n-butylisonitrile corresponds to a thermodynamic well on the potential energy surface. For the formation of the analogous thiocarbonate complex from CO oxidation, however, we do not find a significant thermodynamic driving force. In the protein matrix of the enzyme this species should be further destabilized, as it requires the metal centers to move apart considerably from each other.Electronic Supplementary Material Supplementary material is available for this article at .     

Purification of NADPH-specific indole-3-acetaldehyde reductase from Cucumis sativus by two-dimensional native polyacrylamide gel electrophoresis

NADPH-specific indole-3-acetaldehyde (IAAId) reductase from cucumber ( Cucumis sativus L. 相似文献   

Male-infant relationships in semifree-ranging Barbary macaques (Macaca sylvanus) of affenberg salem/FRG: Testing the “male care” hypothesis

The infant-directed behavior of Barbary macaque males was analyzed in order to determine whether it is essential for an infant's survival during the first year and whether males interact selectively with closely related infants. Dyadic male-infant contacts were recorded in a large group of semifree-ranging Barbary macaques. Data collected during the first 12 weeks of life on each infant born in 1983 (n = 36) were analyzed. All adult and almost all subadult males established strong relationships with at least one infant. Almost two-thirds of the infants (22) had frequent contacts with one or several males. Males showed no preference for closely related infants. Sexual associations with an infant's mother during the preceding mating season had no significant effect. Natal males did not prefer infants of their own matrilineage. There was no evidence that contacts with males had a positive influence on infant survival or that other benefits to the infants resulted from these contacts. Instead, excessive carrying by males and females led to starvation of some very young infants and was a major cause of neonatal deaths in this population. Males interacted preferentially with infants that were born early in the birth season, had a high-ranking multiparous mother, and were male. Younger males established strong relationships with male infants only, while mother's rank was more important for older males. It is suggested that certain mothers prevented early contacts between their infants and males so that the observed preferences for certain infants were also a result of easier access to them. All results suggested that males interacted with infants for their own benefit.     

Microbially influenced corrosion and rust tubercle formation on sheet piles in freshwater systems

The extent of how complex natural microbial communities contribute to metal corrosion is still not fully resolved, especially not for freshwater environments. In order to elucidate the key processes, we investigated rust tubercles forming massively on sheet piles along the river Havel (Germany) applying a complementary set of techniques. In-situ microsensor profiling revealed steep gradients of O₂, redox potential and pH within the tubercle. Micro-computed tomography and scanning electron microscopy showed a multi-layered inner structure with chambers and channels and various organisms embedded in the mineral matrix. Using Mössbauer spectroscopy we identified typical corrosion products including electrically conductive iron (Fe) minerals. Determination of bacterial gene copy numbers and sequencing of 16S rRNA and 18S rRNA amplicons supported a densely populated tubercle matrix with a phylogenetically and metabolically diverse microbial community. Based on our results and previous models of physic(electro)chemical reactions, we propose here a comprehensive concept of tubercle formation highlighting the crucial reactions and microorganisms involved (such as phototrophs, fermenting bacteria, dissimilatory sulphate and Fe(III) reducers) in metal corrosion in freshwaters.     

Nanopartikel in Konsumgütern

Nanoparticles in products – risks and benefits Nanotechnology is using the improved properties of materials in the size range of billionths of a meter. Thus, nanoparticles are used as beneficial additives in many areas of life such as cosmetics or waterproofing agents. In some cases, they can come into direct contact with consumers themselves. Theoretically, their small size allows them to enter the human body and even individual cells, thus possibly causing unwanted effects. In reality however, many factors other than size also influence this process. The question whether nanoparticles are hazardous is similarly difficult to answer as the question whether chemicals are harmful: the term includes too great a variety of forms, materials and sizes to give one answer for all nanomaterials, which have to be regarded separately. Accompanying the developing process of new nanomaterials, safety research has to be carried out in order to identify possible harmful effects.