Generalist predator's niche shifts reveal ecosystem changes in an experimentally fragmented landscape

Habitat fragmentation can alter the trophic structure of communities and environmental conditions, thus driving changes in biodiversity and ecosystem functions. Quantifying niches of generalist predators can reveal how fragmentation alters ecosystems. In a habitat fragmentation experiment, we used stable isotopes of a generalist predator skink to test predictions from spatial theory on trophic structure and to quantify abiotic changes associated with fragmentation among continuous forest, fragments, and matrix habitats. We predicted that in fragments and the matrix, isotopic niches would shift due to decreases in skink trophic positions (δ¹⁵N) from reductions in trophic structure of arthropod food webs and abiotic changes over time (δ¹³C) relative to continuous forest. Contrary to theoretical predictions, we did not find evidence of reductions in trophic structure with fragmentation. In fact, skink δ¹⁵N values were higher in the matrix and fragments than continuous forest, likely due to changes in distributions of a detritivorous prey species. In addition, δ¹³C values in the matrix decreased over years since fragmentation due to abiotic changes associated with matrix tree maturation. We show how isotopic niches are influenced by fragmentation via shifts in biotic and abiotic processes. The potential for either or both spatial and abiotic effects of fragmentation present a challenge for theory to better predict ecological changes in fragmented landscapes.     

An electron microscopic study of the Golgi apparatus of amphibian oocytes

Conclusion An electron microscope study of the Golgi complex was carried out using amphibian oocytes both prior to and after vitellogenesis. In the former case it was noted that the Golgi complex consists of small vesicles and cisternae. After yolk formation, each Golgi mass was found to consist only of (a smaller number of) cisternae. The distribution, function, and multiplication of the Golgi material were also discussed.This work was supported by U.S.P.H.S. research grant RG 5803 (C 2) and was carried out during the course of a U.S.P.H.S. Special Research Fellowship (GF—5356—C 2).     

CONGESTIVE HEART FAILURE IN INFANTS AND CHILDREN

Congestive failure in infants and children is not uncommon and may be present in a varying number of conditions, particularly in certain types of congenital heart disease. Its recognition and proper treatment are usually followed by improvement, except in those instances where the failure is associated with a lesion incompatible with life. The essentials of treatment are: Treatment of the underlying cause, administration of a digitalis preparation, low salt diet, diuretics, rest and sedation, oxygen, adequate diet and, in rare instances, the use of steroids.     

An Inexpensive Inverted Microscope System

An inexpensive and easily constructable inverted microscope system is described in detail. Its multiple experimental usefulness in many branches of biology is mentioned.