Primary Succession on a Hawaiian Dryland Chronosequence

We used measurements from airborne imaging spectroscopy and LiDAR to quantify the biophysical structure and composition of vegetation on a dryland substrate age gradient in Hawaii. Both vertical stature and species composition changed during primary succession, and reveal a progressive increase in vertical stature on younger substrates followed by a collapse on Pleistocene-aged flows. Tall-stature Metrosideros polymorpha woodlands dominated on the youngest substrates (hundreds of years), and were replaced by the tall-stature endemic tree species Myoporum sandwicense and Sophora chrysophylla on intermediate-aged flows (thousands of years). The oldest substrates (tens of thousands of years) were dominated by the short-stature native shrub Dodonaea viscosa and endemic grass Eragrostis atropioides. We excavated 18 macroscopic charcoal fragments from Pleistocene-aged substrates. Mean radiocarbon age was 2,002 years and ranged from < 200 to 7,730. Genus identities from four fragments indicate that Osteomeles spp. or M. polymorpha once occupied the Pleistocene-aged substrates, but neither of these species is found there today. These findings indicate the existence of fires before humans are known to have occupied the Hawaiian archipelago, and demonstrate that a collapse in vertical stature is prevalent on the oldest substrates. This work contributes to our understanding of prehistoric fires in shaping the trajectory of primary succession in Hawaiian drylands.     

The microbial degradation of morpholine

Morpholine can be completely degraded microbiologically, and two organisms have been isolated, each capable of growth in a simple mineral salts medium with morpholine as the sole source of carbon, nitrogen and energy. Excess nitrogen is liberated as ammonia. The enzymes responsible for the oxidation of morpholine are inducible and, in organism Mor G, will also oxidize piperidine, piperazine and pyrrolidine, which are not growth substrates. Ethanolamine is a likely intermediate, though the metabolic steps in morpholine degradation do not give rise solely to acetyl-CoA. After a period of acclimation, a laboratory scale activated sludge plant effectively removed morpholine over the long period it was operated; the sludge was also capable of nitrification. The possible effects of other chemicals in trade wastes containing morpholine on nitrification and morpholine oxidation are described.     

Retinoic acid induction of featherlike structures from reticulate scales

Retinoic acid-induced transformation of reticulate scales to feather-like structures (Dhouailly and Hardy, '78) provides a useful model to study biochemical differentiation in avian skin. In this study, immunofluorescent analysis of reticulate scale-feathers (RSFs) indicates that they contain beta keratin in feather barbs and, thus, are true feathers, biochemically. Epidermal cells that would otherwise produce only alpha keratin in reticulate scales are induced to reorganize and differentiate into barb ridge cells that accumulate feather beta keratins. The mechanism for these dramatic morphological and biosynthetic responses to retinoic acid is unknown.     

Hepatikologische Studien. I. Ist die Entwicklung des Lebermoosperianths von der Befruchtung Abhängig?

Ohne ZusammenfassungMit 1 Textabbildung     

Über die Ausscheidung von Aminosäuren in reinen und gemischten Beständen verschiedener Pflanzenarten

Ohne Zusammenfassung