Evidence for species differences in the pattern of androgen receptor distribution in relation to species differences in an androgen‐dependent behavior

Chickens (Gallus gallus domesticus) and Japanese quail (Coturnix japonica), two closely related gallinaceous bird species, exhibit a form of vocalization—crowing—which differs between the species in two components: its temporal acoustic pattern and its accompanying postural motor pattern. Previous work utilizing the quail‐chick chimera technique demonstrated that the species‐specific characteristics of the two crow components are determined by distinct brain structures: the midbrain confers the acoustic pattern, and the caudal hindbrain confers the postural pattern. Crowing is induced by androgens, acting directly on androgen receptors. As a strategy for identifying candidate neurons in the midbrain and caudal hindbrain that could be involved in crow production, we performed immunocytochemistry for androgen receptors in these brain regions in both species. We also investigated midbrain‐to‐hindbrain vocal‐motor projections. In the midbrain, both species showed prominent androgen receptor immunoreactivity in the nucleus intercollicularis, as had been reported in previous studies. In the caudal hindbrain, we discovered characteristic species differences in the pattern of androgen receptor distribution. Chickens, but not quail, showed strong immunoreactivity in the tracheosyringeal division of the hypoglossal nucleus, whereas quail, but not chickens, possessed strong immunoreactivity in a region of the ventrolateral medulla. Some of these differences in hindbrain androgen receptor distribution may be related to the species differences in the postural component of crowing behavior. The results of the present study imply that the spatial distribution of receptor proteins can vary even between closely related species. Such variation in receptor distribution could underlie the evolution of species differences in behavior. © 2002 Wiley Periodicals, Inc. J Neurobiol 52: 203–220, 2002     

Strategies for signal amplification in nucleic acid detection

Many aspects of molecular genetics necessitate the detection of nucleic acid sequences. Current approaches involving target amplification (in situ PCR, Primed in situ Labeling, Self-Sustained Sequence Replication, Strand Displacement Amplification), probe amplification (Ligase Chain Reaction, Padlock Probes, Rolling Circle Amplification) and signal amplification (Tyramide Signal Amplification, Branched DNA Amplification) are summarized in the present review, together with their advantages and limitations.     

Tapetoretinal Degeneration in Childhood Presenting as a Disturbance of Behaviour

Four children presented at the age of 6 years with progressive disturbances of behaviour due to increasing visual handicap. In three of them routine ophthalmological examination was carried out in the early stages, but no objective evidence of eye disease was found. The severity and nature of the visual defect and its causal relationship to the behaviour disorder went unrecognized for periods ranging from 18 to 30 months. Eventually the development of retinal changes enabled a diagnosis of tapetoretinal degeneration to be made which was confirmed by the finding of extinction of the electroretinographic response. Transfer of the children to schools for the visually handicapped resulted in improvement in their behaviour disorder.Electroretinography is of great importance in the early diagnosis of juvenile tapetoretinal degeneration.     

Sedimentation in fluvial and lacustrine environments

Sedimentation in rivers is dominated by a complex set of physical processes, associated with the unidirectional flow of water. Variations in these processes give rise to different fluvial channel types, whose character can commonly be recognised in the ancient record. Chemical and biological processes are comparatively unimportant in fluvial sedimentation. In contrast, physical, chemical or biological processes can each dominate sedimentation in lakes. Physical (clastic) deposition dominates in high-latitude and mountain lakes (in which chemical and biological activity are low), and in lakes with high relief of the drainage basin and lake floor. Its variety reflects a range of processes influenced by river inflow, wave and current action, thermal and density effects. Economic benefits from the study of lake and river sedimentation include both resource and environmental aspects. An example is given of a mercury pollution study in a fluvial ecosystem. It shows that return to background levels can take place within a relatively short interval after cessation of pollutant input.     

Successful captive breeding of Mitchell's water monitor,Varanus mitchelli (Mertens 1958), at Perth Zoo

Mitchell's water monitors (Varanus mitchelli) have been maintained on display at Perth Zoo since 1997. They are generally a timid species but have been maintained and bred in a mixed species water feature exhibit. In this article we describe their captive management and behavior with an insight into their reproductive biology. Between 2002 and 2005, 11 clutches were laid ranging from 13 to 27 (X? = 20) eggs from one female. Egg size ranged between 3.00 and 6.08 g (X? = 4.77 g) in weight, 22.8 and 31.9 mm (X? = 28.3 mm) in length, and 11.1 and 19.3 mm (X? = 17.1 mm) in width. Oviposition included double and triple clutches ranging between 41 and 60 days apart (X? = 48 days), events n = 6. Four clutches were incubated at three different temperatures and hatchlings emerged after 157–289 days. The weight of the hatchlings ranged between 2.60 and 4.52 g (X? = 4.34 g). Total length ranged between 140.1 and 178.0 mm (X? = 165.9 mm) and snout–vent length ranged from 53.8 to 70.0 (X? = 64.4 mm). Juvenile growth and development information is presented from hatching through to approximately 3 years of age. Zoo Biol 29:615–625, 2010. © 2009 Wiley‐Liss, Inc.     

Spatial Structure and Diffusive Dynamics from Single-Particle Trajectories Using Spline Analysis

Single-particle tracking of biomolecular probes has provided a wealth of information about intracellular trafficking and the dynamics of proteins and lipids in the cell membrane. Conventional mean-square displacement (MSD) analysis of single-particle trajectories often assumes that probes are moving in a uniform environment. However, the observed two-dimensional motion of probe particles is influenced by the local three-dimensional geometry of the cell membrane and intracellular structures, which are rarely flat at the submicron scale. This complex geometry can lead to spatially confined trajectories that are difficult to analyze and interpret using conventional two-dimensional MSD analysis. Here we present two methods to analyze spatially confined trajectories: spline-curve dynamics analysis, which extends conventional MSD analysis to measure diffusive motion in confined trajectories; and spline-curve spatial analysis, which measures spatial structures smaller than the limits of optical resolution. We show, using simulated random walks and experimental trajectories of quantum dot probes, that differences in measured two-dimensional diffusion coefficients do not always reflect differences in underlying diffusive dynamics, but can instead be due to differences in confinement geometries of cellular structures.