Feeding through artificial membranes reduces fecundity for females of the blood‐feeding insect,Rhodnius prolixus

The blood‐feeding insect, Rhodnius prolixus, has been raised in the laboratory for close to 100 years. Various feeding techniques have been employed ranging from the use of warm‐blooded hosts, to the use of previously collected blood offered through artificial membranes. This study compared the fecundity in mated and unmated females fed rabbit blood directly from the shaved belly of a rabbit to that of females fed defibrinated rabbit blood through an artificial membrane. These results confirm previous reports that this insect's feeding efficacy is reduced using an artificial membrane. It also demonstrates for the first time that the fecundity index, which measures the efficiency of turning the blood meal into eggs, is significantly reduced. We suggest that the natural feeding on a warm‐blooded host may provide cues that have the short‐term effect of enhancing the act of feeding and the long‐term effect of increasing egg production efficiency. Until an artificial feeding method that does not interfere with feeding and fecundity is devised, experiments on reproduction in R. prolixus warrant the use of a warm‐blooded host to emulate feeding in its natural setting. © 2010 Wiley Periodicals, Inc.     

Functional morphology of digestion in the stomachless,piscivorous needlefishes Tylosurus gavialoides and Strongylura leiura ferox (Teleostei: Beloniformes)

Belonidae are unusual in that they are carnivorous but lack a stomach and have a straight, short gut. To develop a functional morphological model for this unusual system the gut contents and alimentary tract morphology of Tylosurus gavialoides and Strongylura leiura ferox were investigated. The posterior orientation of the majority of the pharyngeal teeth supports the swallowing of whole large prey, but not their mastication. Mucogenic cells are abundant in the mucosa lining, particularly the esophagus, and their secretions are likely to protect the gut lining from damage while lubricating passage of the prey. Esophagus, anterior intestine, posterior intestine, and rectum all have highly reticulate mucosae. The anterior three gut sections are distensible to accommodate the passage of prey. However, following ingestion large prey are passed to the highly distensible posterior intestine where they rest head first against the ileorectal valve. Alimentary pH ranges from neutral to weakly acidic. Fish prey is digested head first with the head being largely digested while the remainder of the body is still intact. The nondistensibility of the rectum and the small aperture provided by the ileorectal valve suggest the products of intestinal digestion are either small particulates or fluids that pass into rectum where they are absorbed. J. Morphol. 2009. © 2009 Wiley‐Liss, Inc.     

Behavioural interactions and activity of captive Eledone moschata: laboratory investigations of a ‘social’ octopus

Because it is found aggregated in its normal environment and is tolerant of the presence of conspecifics in the laboratory, Eledone has been designated as a ‘social’ octopus. Behavioural observations of Eledone moschata confirmed that individuals interacted often, did not always move away from one another when touched and did not often withdraw into available shelters. However, E. moschata also formed a size-based dominance hierarchy, as do several species of Octopus in captivity. This parallel may mean that the apparent differences in social organization of octopods are quantitative rather than qualitative.     

Profile of estrogen‐responsive genes in an estrogen‐specific mammary gland outgrowth model

Both ovarian and pituitary hormones are required for the pubertal development of the mouse mammary gland. Estradiol directs ductal elongation and branching, while progesterone leads to tertiary branching and alveolar development. The purpose of this investigation was to identify estrogen‐responsive genes associated with pubertal ductal growth in the mouse mammary gland in the absence of other ovarian hormones and at different stages of development. We hypothesized that the estrogen‐induced genes and their associated functions at early stages of ductal elongation would be distinct from those induced after significant ductal elongation had occurred. Therefore, ovariectomized prepubertal mice were exposed to 17β‐estradiol from two to 28 days, and mammary gland global gene expression analyzed by microarray analysis at various times during this period. We found that: (a) gene expression changes in our estrogen‐only model mimic those changes that occur in normal pubertal development in intact mice, (b) both distinct and overlapping gene profiles were observed at varying extents of ductal elongation, and (c) cell proliferation, the immune response, and metabolism/catabolism were the most common functional categories associated with mammary ductal growth. Particularly striking was the novel observation that genes active during carbohydrate metabolism were rapidly and robustly decreased in response to estradiol. Lastly, we identified mammary estradiol‐responsive genes that are also co‐expressed with estrogen receptor α in human breast cancer. In conclusion, our genomic data support the physiological observation that estradiol is one of the primary hormonal signals driving ductal elongation during pubertal mammary development. Mol. Reprod. Dev. 76: 733–750, 2009. Published 2009 Wiley‐Liss, Inc.     

SIMULATED VESSEL APPROACHES ELICIT DIFFERENTIAL RESPONSES FROM MANATEES

One of the most pressing concerns associated with conservation of the endangered Florida manatee is mortality and serious injury due to collisions with watercraft. Watercraft collisions are the leading identified cause of manatee mortality, averaging 25% and reaching 31% of deaths each year. The successful establishment and management of protected areas depend upon the acquisition of data assessing how manatees use different habitats, and identification of environmental characteristics influencing manatee behavior and habitat selection. Acoustic playback experiments were conducted to assess the behavioral responses of manatees to watercraft approaches. Playback stimuli made from prerecorded watercraft approaches were constructed to simulate a vessel approach to approximately 10 m in sea grass habitats. Stimulus categories were (1) silent control, (2) approach with outboard at idle speed, (3) vessel approach at planning speed, and (4) fast personal watercraft approach. Analyses of swim speed, changes in behavioral state, and respiration rate indicate that the animals responded differentially to the playback categories. The most pronounced responses, relative to the controls, were elicited by personal watercraft. Quantitative documentation of response during playbacks provides data that may be used as the basis for future models to predict the impact of specific human activities on manatees and other marine mammal populations.