Real-time observation of molecular motion on a surface

The laser-induced movement of CO molecules over a platinum surface was followed in real time by means of ultrafast vibrational spectroscopy. Because the CO molecules bound on different surface sites exhibit different C-O stretch vibrational frequencies, the site-to-site hopping, triggered by excitation with a laser pulse, can be determined from subpicosecond changes in the vibrational spectra. The unexpectedly fast motion--characterized by a 500-femtosecond time constant--reveals that a rotational motion of the CO molecules, rather than pure translation, is required for this diffusion process. This conclusion is corroborated by density functional theory calculations.     

Structural dynamics of eukaryotic chromosome evolution

Large-scale genome sequencing is providing a comprehensive view of the complex evolutionary forces that have shaped the structure of eukaryotic chromosomes. Comparative sequence analyses reveal patterns of apparently random rearrangement interspersed with regions of extraordinarily rapid, localized genome evolution. Numerous subtle rearrangements near centromeres, telomeres, duplications, and interspersed repeats suggest hotspots for eukaryotic chromosome evolution. This localized chromosomal instability may play a role in rapidly evolving lineage-specific gene families and in fostering large-scale changes in gene order. Computational algorithms that take into account these dynamic forces along with traditional models of chromosomal rearrangement show promise for reconstructing the natural history of eukaryotic chromosomes.     

In Memoriam

Ohne Zusammenfassung     

The effect of albendazole on nematode parasites in experimentally infected lambs.

Thirty-five complete oestrous cycles were studied in five nonpregnant camels (Camelus dromedarius) over a period of 15 months. The oestrous cycle did not have a luteal phase. During the cycle of 28 days the ovarian activity was strictly follicular. Follicles matured in six days, maintained their size for 13 days and regressed in eight days. Ovulation was non-spontaneous and required the stimulus of coitus. Manual stimulation of the cervix for 15 minutes did not induce ovulation. The external manifestations of the oestrous cycle as well as the changes in the ovaries and the genital tract were also studied.     

Handbuch der Insektizidkunde

Ohne Zusammenfassung     

Effect of organic,inorganic, and combined organic and inorganic P fertilization on plant P uptake and soil P pools

Phosphorus (P) is a limited resource, and its efficient use is a main task in sustainable agriculture. In a 6‐year field experiment on a loamy‐sand soil poor in P, the effects of organic, inorganic, and combined organic‐inorganic fertilization on crop yield, P uptake into grain, and soil properties (organic matter [OM] content, pH, water‐extractable P [P_w], double lactate–extractable P [P_dl], oxalate‐extractable P [P_ox], P‐sorption capacity [PSC], and degree of P saturation [DPS]) were investigated for the maritime climate in northeast Germany. Nine treatments were compared: a control treatment without fertilizer application, two organic fertilizers (cattle manure [CM] and biowaste compost [BC]; applied at a rate of 30 t ha^–1 in autumn 1998 and 2001), application of triple‐superphosphate (TSP; applied once a year either in autumn or in spring to evaluate the effects of application date), and combinations of organic and inorganic fertilizations. Several winter and spring crops (oilseed rape, barley, wheat) were cultivated according to good agricultural practice. The 6 year–average yield and P uptake were significantly higher for fertilized plots than for nonfertilized plots. Although the combination of organic × inorganic fertilizers resulted in higher soil P contents, significant yield increases were only found when organic fertilization was combined with TSP in spring. Small effects of P supply on yield in some years indicate that plant‐available soil P (despite of low P_dl values) was sufficient for crop growth. Phosphorus supply affected soil P_dl and P_w more than the parameters measured in the oxalate extract (P_ox, PSC, DPS). In general, periodically applied cattle manure and biowaste compost had the same effect on yield, P uptake, and soil P status as annually applied soluble mineral P.