Modifications of the genital kidney proximal and distal tubules for sperm transport in Notophthalmus viridescens (Amphibia,Urodela, Salamandridae)

Male salamanders use nephrons from the genital kidney to transport sperm from the testicular lobules to the Wolffian duct. The microstructure of the epithelia of the genital kidney proximal tubule and distal tubule was studied over 1 year in a population of Notophthalmus viridescens from Crawford and Pike counties in central Missouri. Through ultrastructural analysis, we were able to support the hypothesis that the genital kidney nephrons are modified to aid in the transportation of sperm. A lack of folding of the basal plasma membrane, in both the genital kidney proximal and distal tubules when compared to the pelvic kidney proximal and distal tubules, reduces the surface area and thus likely decreases the efficiency of reabsorption in these nephron regions of the genital kidney. Ciliated epithelial cells are also present along the entire length of the genital kidney proximal tubule, but are lacking in the epithelium of the pelvic kidney proximal tubule. The exact function of these cilia remains unknown, but they may aid in mixing of seminal fluids or the transportation of immature sperm through the genital kidney nephrons. Ultrastructural analysis of proximal and distal tubules of the genital kidney revealed no seasonal variation in cellular activity and no mass production of seminal fluids throughout the reproductive cycle. Thus, we failed to support the hypothesis that the cellular activity of the epithelia lining the genital kidney nephrons is correlated to specific events in the reproductive cycle. The cytoplasmic contents and overall structure of the genital and pelvic kidney epithelial cells were similar to recent observations in Ambystoma maculatum, with the absence of abundant dense bodies apically in the epithelial cells lining the genital kidney distal tubule. J. Morphol. 275:914–922, 2014. © 2014 Wiley Periodicals, Inc.     

Environmental quality mediates the ecological dominance of cooperatively breeding birds

Although social species as diverse as humans and ants are among the most abundant organisms on Earth, animals cooperate and form groups for many reasons. How these different reasons for grouping affect a species' ecological dominance remains unknown. Here we use a theoretical model to demonstrate that the different fitness benefits that animals receive by forming groups depend on the quality of their environment, which in turn impacts their ecological dominance and resilience to global change. We then test the model's key predictions using phylogenetic comparative analysis of >6500 bird species. As predicted, we find that cooperative breeders occurring in harsh and fluctuating environments have larger ranges and greater abundances than non-cooperative breeders, but cooperative breeders occurring in benign and stable environments do not. Using our model, we further show that social species living in harsh and fluctuating environments will be less vulnerable to climate change than non-social species.     

Latitudinal species diversity gradient of marine zooplankton for the last three million years

High tropical and low polar biodiversity is one of the most fundamental patterns characterising marine ecosystems, and the influence of temperature on such marine latitudinal diversity gradients is increasingly well documented. However, the temporal stability of quantitative relationships among diversity, latitude and temperature is largely unknown. Herein we document marine zooplankton species diversity patterns at four time slices [modern, Last Glacial Maximum (18 000 years ago), last interglacial (120 000 years ago), and Pliocene (~3.3–3.0 million years ago)] and show that, although the diversity‐latitude relationship has been dynamic, diversity‐temperature relationships are remarkably constant over the past three million years. These results suggest that species diversity is rapidly reorganised as species' ranges respond to temperature change on ecological time scales, and that the ecological impact of future human‐induced temperature change may be partly predictable from fossil and paleoclimatological records.     

Varenicline and nicotine enhance GABAergic synaptic transmission in rat CA1 hippocampal and medial septum/diagonal band neurons

AimsThe FDA approved smoking cessation aid varenicline can effectively attenuate nicotine-stimulated dopamine release. Varenicline may also exert important actions on other transmitter systems that also influence nicotine reinforcement or contribute to the drug's cognitive and affective side effects. In this study, we determined if varenicline, like nicotine, can stimulate presynaptic GABA release.Main methodsUsing whole-cell patch-clamp techniques, we measured GABA_AR-mediated asynchronous, spontaneous miniature inhibitory postsynaptic currents (mIPSCs) in acute brain slices from two brain regions important for learning and memory, the hippocampus and basal forebrain.Key findingsBoth varenicline (10 μM) and nicotine (10 μM) applications alone resulted in small but significant increases in amplitude, as well as robustly enhanced frequency of mIPSCs in hippocampal CA1 pyramidal neurons and medial septum/diagonal band (MS/DB) neurons. A unique subpopulation of MS/DB neurons showed decreases in frequency. In the presence of nicotine, varenicline effectively attenuated the expected enhancement of hippocampal mIPSC frequency like a competitive antagonist. However, in the MS/DB, varenicline only partially attenuated nicotine's effects. Reversing the order of drug application by adding nicotine to varenicline-exposed slices had little effect.SignificanceVarenicline, like nicotine, stimulates presynaptic GABA release, and also exerts a partial agonist action by attenuating nicotine-stimulated release in both the hippocampus and basal forebrain. These effects could potentially affect cognitive functions.     

p53 serum antibodies as prognostic indicator in head and neck cancer

p53 antibodies are a new serological parameter of unknown potential in patients with malignancies. Their occurrence has been described in various types of cancer patients. The mechanism underlying the immunization process is still unclear. We investigated the incidence of p53 serum antibodies in 143 head and neck cancer patients with an enzyme-linked immunosorbent assay. The post-therapy course of two matched study groups (n = 38 each), one p53-antibody-seropositive and one p53-antibody-seronegative, was followed up for 24 months. Thirty-nine head and neck cancer patients (27.3%) were seropositive for p53 antibodies. During the follow-up, the p53-antibody-seropositive patients accounted for more local tumor recurrences (n = 12 versus n = 8) and more tumor-related deaths (n = 11 versus n = 5) than did seronegative patients, and second primary tumors (n = 9 versus n = 0) occurred exclusively in seropositive patients. In total, therapy failures (recurrences, tumor-related deaths, second primaries) were observed in 17/38 cases (44.7%) in the p53-antibody-seropositive group and in 8/38 cases (21.1%) in the p53-antibody-seronegative group. These results, after a follow-up of 2 years, seem to indicate a prognostic value of p53 serum antibodies for therapy failure in patients with head and neck cancer. Received: 5 December 1996 / Accepted: 4 January 1997     

Über den feinbau der schillerhaare des polychaeten Aphrodite aculeata L.

Ohne Zusammenfassung