Influence of stochastic processes and catastrophic events on the reproductive dynamics of the endangered Maroon‐fronted Parrot Rhynchopsitta terrisi

Stochastic and catastrophic events may strongly impact the dynamics of wild populations. Annual fluctuations in rainfall may affect parrot populations, but few studies address the impact of other stochastic or catastrophic events on their population dynamics. The Maroon‐fronted Parrot Rhynchopsitta terrisi is an endangered species that nests colonially in cavities and crevices in limestone cliffs. From 1995 to 2010, we quantified Parrot attendance at nesting colonies throughout its breeding range, and reproductive output of nesting Parrots from 1997 to 2010 at the two most important nesting colonies. There was significant variation among colonies in the number of cavities occupied by Parrots each year. Rainfall significantly influenced both the number of occupied cavities and productivity, which declined after very dry years. Natural unpredictable events such as hurricanes did not modify the nesting activity of Maroon‐fronted Parrots at breeding colonies. However, wildfires increased in dry years, negatively affecting attendance at breeding colonies. The Maroon‐fronted Parrot may overcome the impacts of climatic variability, natural stochastic processes, and human‐induced catastrophic events by using nesting colonies as a network of resources throughout the breeding range. Given the current trends in climate change, it is likely the species may suffer stronger and more frequent unpredictable catastrophic events, potentially putting at risk its survival in the long term.     

Solution structures and model membrane interactions of Ctriporin,an anti‐methicillin‐resistant Staphylococcus aureus Peptide from Scorpion Venom

Ctriporin peptide (Ctr), a novel antimicrobial peptide isolated from the venom of the scorpion Chaerilus tricostatus, shows a broad‐spectrum of antimicrobial activity and is able to inhibit antibiotic resistant pathogens, including Methicillin resistant Staphylococcus aureus, Methicillin Resistant Coagulase‐negative Staphylococcus, and Penicillin Resistant Staphylococcus epidermidis strains. To understand the active conformation of the Ctr peptide in membranes, we have investigated the interaction of Ctr with the negatively charged and zwitterionic membrane‐mimetic micelles such as sodium dodecyl sulphate (SDS) and n‐dodecylphosphocholine (DPC), respectively. The interactions were studied using fluorescence and circular dichroism (CD) spectroscopy. Fluorescence experiments revealed that the N‐terminus tryptophan residue of Ctr interacted with the hydrophobic core of the membrane mimicking micelles. The CD results suggest that interactions with membrane‐mimetic micelles induce an α‐helix conformation in Ctr. Moreover, we have determined the solution structures of Ctr in SDS and DPC micelles using nuclear magnetic resonance (NMR) spectroscopy. The structural comparison of Ctr in the presence of SDS and DPC micelles showed significant conformational changes. The observed structural differences of Ctr in anionic versus zwitterionic membrane‐mimetic micelles suggest that the mode of interaction of this peptide may be different in two environments which may account for its ability to differentiate bacterial and eukaryotic cell membrane. © 2014 Wiley Periodicals, Inc. Biopolymers 101: 1143–1153, 2014.     

Morphophysiology of the paracloacal (scent) glands in females of the marsupial Metachirus nudicaudatus: action of estrogens

The histophysiology of both brown and yellow paracloacal glands of control animals from wild populations was analyzed in the breeding and non-breeding seasons and in oophorectomized animals. The effect of estrogens on the scent glands of female Metachirus nudicaudatus was investigated. Radioimmunoassay indicated that estradiol levels in the breeding season were high, while those in the non-breeding season and oophorectomized had minute amounts. No apparent change in gland volume was observed in the various animal groups. Light microscopy showed a wide variation in the number of layers of the holocrine secretory epithelium of the major (brown) gland between the breeding (1–7) and non-breeding season (8–19) and in oophorectomized (8–18) animals. The minor (yellow) gland showed the most evident variation: the holocrine epithelium was restricted to the basal layer in the breeding season, but was restored and exhibited up to eight layers in the non-breeding season and in oophorectomized females. The mean cellular area of the secretory holocrine epithelium in the breeding season was smaller than in the non-breeding period and in castrated animals. On the other hand, the mean cellular areas of tubular glands inserted in both yellow and brown glands in the breeding season were larger than those in the non-breeding season and after castration. The results consistently indicate that the glandular volumes of yellow and brown glands do not depend on estrogens, whereas the holocrine secretory epithelium and tubular glands of both are estrogenic modulation.     

How Old are Colonizing Hypothenemus hampei (Ferrari) Females When They Leave the Native Coffee Fruit?

The age of colonizing Hypothenemus hampei (Ferrari) females when they leave the native coffee fruit was determined under laboratory conditions. This biological parameter might be useful for planning experiments with this species because certain physiological statuses are expressed from or until a determined age, which in turn may determine the response of individuals to different treatments. An experimental device was used to simulate the conditions inside a coffee berry and to permit the observation of the abandonment behavior of the beetles. Virgin and mated females with or without melanized cuticles were used in the experiments. On average, colonizing coffee berry borers were 15-days-old at the moment of host abandonment. Females at this age were mated, had full dark cuticles, and were able to display flight and lay viable eggs. Interestingly, H. hampei females that mated before they acquire a fully dark cuticle abandoned the host 1.7 times faster than females that mated after they reach this physiological status. Further studies into food conditions and their impacts on the pre- abandonment of H. hampei females are encouraged.