This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited.

Rewilding has been an increasingly popular tool to restore plant-animal interactions and ecological processes impaired by defaunation. However, the reestablishment of such processes has seldom been assessed. We investigated the restoration of ecological interactions following the reintroduction of the brown howler monkey (Alouatta guariba) to a defaunated Atlantic forest site. We expected the reintroduction to restore plant-animal interactions and interactions between howlers and dung beetles, which promote secondary seed dispersal. We estimated the number of interactions expected to be restored by the reintroduction to provide the baseline interaction richness that could be restored. We followed the reintroduced howler monkeys twice a week for 24 months (337 hours total) to assess their diet. We used howler monkey dung in secondary seed dispersal experiments with 2484 seed mimics to estimate the removal rates by dung beetles and collected the beetles to assess community attributes. We compared the potential future contribution of howler monkeys and other frugivores to seed dispersal based on the seed sizes they disperse in other areas where they occur. In 2 years, howler monkeys consumed 60 animal-dispersed plant species out of the 330 estimated. Twenty-one dung beetle species were attracted to experimentally provided dung; most of them were tunnelers, nocturnal, and large-sized (>10 mm). On average 30% (range 0-100%) of the large seed mimics (14 mm) were moved by dung beetles. About 91% of the species consumed by howlers (size range 0.3-34.3 mm) overlapped in seed size with those removed by dung beetles. In our study area, howler monkeys may consume more large-seeded fruit species than most other frugivores, highlighting their potential to affect forest regeneration. Our results show reintroductions may effectively restore ecological links and enhance ecological processes.

The 6P-hydroxylation of taurochenodeoxycholate by rat liver microsomes has been previously reported ( 1 ) . The participation of cytochrome P-450 in this reaction was subsequently demonstrated by the photochemical action spectrum method ( 2 ) . In this respect, the enzyme is similar to a number of other mixed function oxidases involved in steroid and drug hydroxylations. These are complex enzymes which introduce one atom of molecular oxygen into the substrate molecule while reducing the other oxygen atom to water. In the process, electrons flow from NADPH through an electron transport system consisting of a flavoprotein at one end and cytochrome P-450 at the other. The steroid 1 lp-hydroxylase system of bovine adrenal mitochondria has been solubilized and resolved into three components of flavoprotein, nonheme-iron protein, and cytochrome P-450 (3). Mixed function oxidases of liver microsomes have, however, resisted similar attempts at resolution and purification, mainly because of instability of the P-450 towards the various solubilizing agents.Recently, Lu et al. (4) have reported the solubilization of fatty acid o-hydroxylase system from rabbit liver. Fractionation of the soluble preparation yielded a P-450 containing fraction and a TPNH-cytochrome c reductase fraction. The ratio of P-450 to protein in the former fraction was, however, the same as that of the intact microsomes.Using our previous method ( l ) , we have prepared an extract of liver microsomes in 1.0 M phosphate, active in 6 P-hydroxylation after removal of the 105,OOOg pellet. The ratio of P-450 to protein indicated a partial purification of P-450 over that in the original microsomes. The apparent K , for tauro-chenodeoxycholate was estimated at 1.2 )( Since the involvement of P-450 in the 6P-hydroxylase system was established, it became of interest to assess its influence in the overall rate of hydroxylation. We treated the experimental animals with various agents which were expected to alter either the levels of P-450 in the liver, the bile acid pool, or both, and measured in each case the 6P-hydroxylase activity and the concentration of P-450. The agents used were (a) phenobarbital, a known inducer of P-450 (S), (b) cholestyramine, a bile acid sequestering resin which causes an increased production of bile acids (6), (c) thyroxine, which enhances the production of chenodeoxycholic acid (7), and (d) chenodeoxycholate to increase the bile acid pool.Methods. Four groups of five male Sprague-Dawley rats (2 months old), weighing 200-250 g each, were kept in individual cages during a 5-day treatment period: (a) Control group, the animals were fed the regular Purina rat chow. (b) Cholestyramine group, the regular Purina pellets were pulverized and mixed with cholestyramine (Merck, Sharp and Dohme) in proportion of 1 g of resin to 19 g of chow. Pellets of approximately the same size as the original were then formed. Each rat ingested an average of 1 g of resin/day. (c) Phenobarbital group, each rat was injected intraperitoneally 25 mg of sodium pheno...

No abstract

No abstract