Trap Lines Research Articles

Cell-type-specific Labeling of Endogenous Proteins Using the Split GFP System in Drosophila.

i. Accurate identification of the locations of endogenous proteins is crucial for understanding their functions in tissues and cells. However, achieving precise cell-type-specific labeling of proteins has been challenging in vivo . A notable solution to this challenge is the self-complementing split green fluorescent protein (GFP 1-10/11 ) system. In this paper, we present a detailed protocol for labeling endogenous proteins in a cell-type-specific manner using the GFP 1-10/11 system in fruit flies. This approach depends on the reconstitution of the GFP 1-10 and GFP 11 fragments, creating a fluorescence signal. We insert the GFP 11 fragment into a specific genomic locus while expressing its counterpart, GFP 1-10 , through an available Gal4 driver line. The unique aspect of this system is that neither GFP 1-10 nor GFP 11 alone emits fluorescence, enabling the precise detection of protein localization only in Gal4-positive cells expressing the GFP 11 tagged endogenous protein. We illustrate this technique using the adhesion molecule gene teneurin-m ( Ten-m ) as a model, highlighting the generation and validation of GFP 11 protein trap lines via Minos-mediated integration cassette (MiMIC) insertion. Furthermore, we demonstrate the cell-type-specific labeling of Ten-m proteins in the larval brains of fruit flies. This method significantly enhances our ability to image endogenous protein localization patterns in a cell-type-specific manner and is adaptable to various model organisms beyond fruit flies.

Багаторічна динаміка угруповань ссавців у Національному природному парку «Гомільшанські ліси» (2015-2022)

The article analyses survey data of small mammals collected by the method of live trapping on two trap lines, the dynamics of beaver numbers in one of the colonies, and random encounters of roadkill mammals in the Homilshanski Lisy National Nature Park and nearby areas. The data were collected in 2015–2022 during field research. Small mammals were studied on the second, pine barren terrace of the Siverskyi Donets River. Two trap lines (trapping trenches with five traps in each, made of two-litre PET bottles) were laid in the pine forest. The first was in an undamaged area of the forest, and the second was in an area damaged by a grassland fire in 2005 and currently undergoing natural forest ecosystem restoration. A total of six species of small mammals were recorded during the survey period, including Sylvaemus uralensis, Myodes glareolus, Sylvaemus tauricus, Mus musculus, Sorex araneus, Crocidura suaveolens, as well as an unidentified Sylvaemus sp. The research has shown that, during the years of peak numbers, not only the abundance of individual species increases, but also the number of recorded species. The beaver colony, where the surveys were conducted, is located in a floodplain on the left bank of the Siverskyi Donets River in a system of three small lakes interconnected by channels. There are also seasonal peaks in the numbers of roadkill species. In total, 17 species have been recorded dead on the roads, which is almost a third of all mammalian species of the Homilshanski Lisy National Nature Park (as of 2020, 60 species have been registered in the Park). It was found that there is a positive correlation between population increase in different groups of mammals and the frequency of deaths of different groups of mammals and the number of species killed on roads. We identified the places where certain anthropogenic factors (poaching, road repairs) are superimposed on natural phenomena and how this affects the state of fauna protection in the National Nature Park. In general, the population dynamics of mammals over the years correlates with the dynamics of encounters of roadkill birds, reptiles, and amphibians, which we also studied during this period. We have proposed a number of recommendations for developing a strategy for the protection of various species in the National Nature Park and its protected area: measures to reduce the risk of animal death on highways.

Re-assessment of the subcellular localization of Bazooka/Par-3 in Drosophila: no evidence for localization to the nucleus and the neuromuscular junction.

Bazooka/Par-3 (Baz) is an evolutionarily conserved scaffold protein that functions as a master regulator for the establishment and maintenance of cell polarity in many different cell types. In the vast majority of published research papers Baz has been reported to localize at the cell cortex and at intercellular junctions. However, there have also been several reports showing localization and function of Baz at additional subcellular sites, in particular the nuclear envelope and the neuromuscular junction. In this study we have re-assessed the localization of Baz to these subcellular sites in a systematic manner. We used antibodies raised in different host animals against different epitopes of Baz for confocal imaging of Drosophila tissues. We tested the specificity of these antisera by mosaic analysis with null mutant baz alleles and tissue-specific RNAi against baz. In addition, we used a GFP-tagged gene trap line for Baz and a bacterial artificial chromosome (BAC) expressing GFP-tagged Baz under control of its endogenous promoter in a baz mutant background to compare the subcellular localization of the GFP-Baz fusion proteins to the staining with anti-Baz antisera. Together, these experiments did not provide evidence for specific localization of Baz to the nucleus or the neuromuscular junction.

Catch composition of fishes by different types of fishing gears in the Andaman sea, Thailand

The Andaman Sea is a rich ecosystem providing significant ecosystem goods and services for people in coastal areas and these areas have fisheries activities using different fishing gears appropriate for different species and habitats. We assessed catch composition and size distribution of economically important finfish captured by a range of fishing gears employed by commercial and artisanal fishers in three provinces adjacent to the central Andaman Sea of Thailand over a 2-year period. Between January 2019 and December 2021, fishers employed 7 main capture gears: surface gillnet, bottom gillnet, fish trap, handline and hook, trawl, purse seines and light-luring anchovy falling net. Trawling captured the highest diversity of target species (35 species) followed by surrounding net (32 species), fish trap (16 species) hook and line (15 species), surface and bottom gillnet (15 species) and the last one of anchovy falling net (2 species). When comparing size at the first maturation of both target species and bycatch, it was found that the percentage of mature fish caught from artisanal fishing gears was higher than of commercial fishing gear because artisanal gears had better selection of catch, especially fish trap and hook and line. Understanding the operation of fishing gears, catch composition and the size frequencies of target species could be particularly important for stock assessment because gear may influence catch composition.

Comparative exploration of mammalian deafness gene homologues in the Drosophila auditory organ shows genetic correlation between insect and vertebrate hearing.

Johnston's organ, the Drosophila auditory organ, is anatomically very different from the mammalian organ of Corti. However, recent evidence indicates significant cellular and molecular similarities exist between vertebrate and invertebrate hearing, suggesting that Drosophila may be a useful platform to determine the function of the many mammalian deafness genes whose underlying biological mechanisms are poorly characterized. Our goal was a comprehensive screen of all known orthologues of mammalian deafness genes in the fruit fly to better understand conservation of hearing mechanisms between the insect and the fly and ultimately gain insight into human hereditary deafness. We used bioinformatic comparisons to screen previously reported human and mouse deafness genes and found that 156 of them have orthologues in Drosophila melanogaster. We used fluorescent imaging of T2A-GAL4 gene trap and GFP or YFP fluorescent protein trap lines for 54 of the Drosophila genes and found 38 to be expressed in different cell types in Johnston's organ. We phenotypically characterized the function of strong loss-of-function mutants in three genes expressed in Johnston's organ (Cad99C, Msp-300, and Koi) using a courtship assay and electrophysiological recordings of sound-evoked potentials. Cad99C and Koi were found to have significant courtship defects. However, when we tested these genes for electrophysiological defects in hearing response, we did not see a significant difference suggesting the courtship defects were not caused by hearing deficiencies. Furthermore, we used a UAS/RNAi approach to test the function of seven genes and found two additional genes, CG5921 and Myo10a, that gave a statistically significant delay in courtship but not in sound-evoked potentials. Our results suggest that many mammalian deafness genes have Drosophila homologues expressed in the Johnston's organ, but that their requirement for hearing may not necessarily be the same as in mammals.

СООБЩЕСТВА МЕЛКИХ МЛЕКОПИТАЮЩИХ СЕВЕРНОЙ ЛЕСОСТЕПИ ТОБОЛО-ИШИМСКОГО МЕЖДУРЕЧЬЯ

The paper summarises the material on the communities of small mammals in the northern forest-steppe of the Tobol-Ishim interfluve (the South Trans-Ural region). A brief history of the study of this group of animals is reviewed. The use of two accounting methods (cones with guide systems and trap lines) made it possible to identify the species composition most fully. 18 species of insectivores and rodents have been registered in the studied territory. At the same time, the species composition, the group of background and dominant species, and the indicators of the total abundance of small mammals in the studied territory were largely determined by the specifics of the animal accounting method. The core of small mammals of the northern forest-steppe of the Tobolo-Ishim interfluve consisted of species tending to moistened habitats – common and pigmy shrew. In general, regardless of the method of accounting animals, they were characterized by low abundance in the study period.

Biotope preferences in groups of closely related species: a case study of Sylvaemus (Mammalia)

The trapping of small mammals was carried out in 2017 to 2023 in the territory of the Kharkiv Oblast, Ukraine. In total, 19 biotopes were studied: different types of oak forest, dry and floodplain meadows, riparian vegetation, areas of the steppe, field protection forest strips, fields, as well as various ecotones. The trapping of small mammals was carried out using the standard trap-line method on 93 trap lines. With a trapping effort of 17 310 trap-nights, 1295 individuals of small mammals were caught, 689 of which belonged to the genus Sylvaemus. Three species of mice of the genus Sylvaemus were found in the territory of Kharkiv Oblast during the study period: Sylvaemus uralensis, Sylvaemus sylvaticus, and Sylvaemus tauricus. According to the relative abundance, wood mice can be arranged in the following order: uralensis > sylvaticus > tauricus. The cyclicity of annual fluctuations in relative abundance is not noticeable. The similarity of the abundance fluctuation in S. sylvaticus and S. tauricus was revealed, taking into account that these are competing species. S. uralensis and S. sylvaticus lead the top three dominant species in the overall dominance structure of small mammals. The highest relative abundance of wood mice during the study period was recorded on dry meadows, on the border of riparian vegetation with fields and floodplain meadows, on the border of field protective forest strips with fields, and in dry maple-linden-oak forest. S. uralensis belongs to the eurytopic species, is found in almost all studied biotopes, avoids oak forests, occurs on the edges of forests, dominates in abundance in open biotopes, in particular in the steppe, on dry meadows, riparian vegetation, and field protection forest strips. S. sylvaticus is also prone to eurytopy, it is recorded in significant abundance in both open and forest biotopes, mostly prefers riparian vegetation, field protection forest strips, dry coniferous forest, fresh maple-linden-oak forest and forest edges. S. tauricus is found mostly in forest biotopes, in particular in various types of oak forest and on forest edges, it prefers field protection forest strips with an old stand of oak, linden, and robinia. All three species of mice of the genus Sylvaemus are common species.

Amino-terminal proteolytic fragment of the axon growth inhibitor Nogo-A (Rtn4A) is upregulated by injury and promotes axon regeneration

After adult mammalian central nervous system injury, axon regeneration is extremely limited or absent, resulting in persistent neurological deficits. Axon regeneration failure is due in part to the presence of inhibitory proteins, including NogoA (Rtn4A), from which two inhibitory domains have been defined. When these inhibitory domains are deleted, but an amino-terminal domain is still expressed in a gene trap line, mice show axon regeneration and enhanced recovery from injury. In contrast, when there is no amino-terminal Nogo-A fragment in the setting of inhibitory domain deletion, then axon regeneration and recovery are indistinguishable from WT. These data indicated that an amino-terminal Nogo-A fragment derived from the gene trap might promote axon regeneration, but this had not been tested directly and production of this fragment without gene targeting was unclear. Here, we describe posttranslation production of an amino-terminal fragment of Nogo-A from the intact gene product. This fragment is created by proteolysis near amino acid G214-N215 and levels are enhanced by axotomy. Furthermore, this fragment promotes axon regeneration in vitro and acts cell autonomously in neurons, in contrast to the inhibitory extracellular action of other Nogo-A domains.Proteins interacting with the amino-terminal Nogo-A fragment by immunoprecipitation include HSPA8 (HSC70, HSP7C). Suppression of HSPA8 expression by shRNA decreases axon regeneration from cerebral cortical neurons and overexpression increases axon regeneration. Moreover, the amino-terminal Nogo-A fragment increases HSPA8 chaperone activity. These data provide an explanation for varied results in different gene-targeted Nogo-A mice, as well as revealing an axon regeneration promoting domain of Nogo-A.

Static management presents a simple solution to a dynamic fishery and conservation challenge

Dynamic ocean management, which leverages near real-time data to adaptively shift management in response to changing ocean conditions, is gaining attention as an alternative to static approaches for managing dynamic fisheries challenges. While promising, dynamic management can be data-intensive, costly, and difficult to implement, and its value relative to simpler static approaches should be evaluated before being applied, especially when endangered species and economically crucial fisheries are at risk. Here, we use management strategy evaluation to compare static and dynamic management strategies for reducing humpback whale (Megaptera novaeangliae) entanglement risk in the highly lucrative California Dungeness crab (Metacarcinus magister) trap fishery. We find that simple gear reductions outperform dynamic management strategies across several measures of performance. Gear reductions maintain uninterrupted fishing seasons and high fisheries catch and effectively prevent whale entanglement risk by directly reducing the number of vertical trap lines. Furthermore, gear reductions are robust to delayed openings resulting from biotoxin contamination and low meat quality, do not depend on the availability or accuracy of entanglement risk indicators, add no new management costs or enforcement challenges, and avoid biases in geographical equity. Dynamic management strategies, which proactively or reactively respond to indicators of entanglement risk, struggle to achieve their intended benefits because they are implemented after long logistical delays and because they redistribute rather than reduce entanglement risk. Bycatch threatens protected species and valuable fisheries around the world and models like the one developed here present valuable tools for weighing solutions to complex fisheries and conservation challenges.

Stop me if you can: quantification of the effect of interfaces between plots on the dispersal of Cosmopolites sordidus.

Cosmopolites sordidus is one of the most damaging pests of banana worldwide. To date, most studies addressed the control of this pest at the plot level, without considering the landscape scale whereas between plots dispersion could be important. The aim of this study was to investigate the ability of C. sordidus to cross contrasted field interfaces. The ten following interfaces were investigated: forests, hedgerows, field tracks, grassy areas, finely and coarsely tilled soil zones, ditches with and without water, vegetable gardening zones, and pheromone trap lines. Individually marked weevils were released on one side of the interface and recovered daily on the other side, allowing the estimation of the velocity and the crossing success of C. sordidus for each interface. Highest permeabilities (with a crossing success above 70%) were obtained for vegetable gardening zones, finely tilled soil zones, forests, and coarsely tilled soil zones. Intermediate permeabilities were measured for hedgerows, field tracks, grassy areas, and ditches without water. Only the line of pheromone traps and submerged ditches had a strong barrier effect on C. sordidus, with a crossing success below 12%. Wind strength, percentage of sky, and vegetation height were negatively correlated to the C. sordidus crossing success. Overall, our results showed that only ditches with water and lines of pheromone traps were efficient in stopping the dispersal of C. sordidus. The next step will be to conduct research to incorporate the use of these two interfaces at farm and landscape scale into integrated pest management strategies. This article is protected by copyright. All rights reserved.

An enhancer trap system to track developmental dynamics in Marchantia polymorpha.

A combination of streamlined genetics, experimental tractability and relative morphological simplicity compared to vascular plants makes the liverwort Marchantia polymorpha an ideal model system for studying many aspects of plant biology. Here we describe a transformation vector combining a constitutive fluorescent membrane marker with a nuclear marker that is regulated by nearby enhancer elements and use this to produce a library of enhancer trap lines for Marchantia. Screening gemmae from these lines allowed the identification and characterization of novel marker lines, including markers for rhizoids and oil cells. The library allowed the identification of a margin tissue running around the thallus edge, highlighted during thallus development. The expression of this marker is correlated with auxin levels. We generated multiple markers for the meristematic apical notch region, which have different spatial expression patterns, reappear at different times during meristem regeneration following apical notch excision and have varying responses to auxin supplementation or inhibition. This reveals that there are proximodistal substructures within the apical notch that could not be observed otherwise. We employed our markers to study Marchantia sporeling development, observing meristem emergence as defining the protonema-to-prothallus stage transition, and subsequent production of margin tissue during the prothallus stage. Exogenous auxin treatment stalls meristem emergence at the protonema stage but does not inhibit cell division, resulting in callus-like sporelings with many rhizoids, whereas pharmacologically inhibiting auxin synthesis and transport does not prevent meristem emergence. This enhancer trap system presents a useful resource for the community and will contribute to future Marchantia research.

Puumala orthohantavirus circulation in its wild reservoir, the bank vole, during the 2021 outbreak of hemorrhagic fever with renal syndrome in Jura, France

ObjectiveA large and unprecedented outbreak of an attenuated form of hemorrhagic fever with renal syndrome called nephropathia epidemica (NE) and caused by Puumala virus (PUUV) occurred in 2021 in the southern Jura Mountains (France) leading to numerous hospitalizations. The aim of this study was to investigate the circulation of PUUV in its animal reservoir at the time of this outbreak. MethodsWe conjointly surveyed bank vole relative abundance, small mammal community composition, and PUUV circulation in bank voles (seroprevalence and genetic diversity) in the Jura NE epidemic area, between 2020 and 2022. ResultsTrapping results showed a higher relative abundance of bank voles in 2021 compared to 2020 and 2022. Extremely high levels of PUUV seroprevalence in bank voles were found at the time of the human NE epidemic with seropositive animals trapped in almost all trap lines as of spring 2021. Genetic analyses of PUUV (S segment) gathered in 2021 at two sampling sites revealed a strong clustering of these strains within the “Jura” clade. No significant genetic variation was detected compared to what was already known to be circulating in the Jura region. ConclusionThese results underline a need for enhanced monitoring of PUUV circulation in host reservoir populations in NE endemic areas. This would enable the relevant actors to better inform and sensitize the public on this zoonotic risk, and to implement prevention strategies in collaboration with physicians.

Does small mammal species richness have a bimodal elevation gradient in Sikkim Himalaya?

The most reported elevation gradients in species richness are a unimodal peak and linear decline. However, the overlap of different biogeographic realms in a region can influence such gradients. We used live-capture data on small mammals (voles, rats, mice, shrews, and pikas) to describe elevation gradients in species richness in Sikkim, where Afrotropical, Indo-Malayan, and Palearctic fauna occur in the lower, middle, and higher elevations, respectively. We sampled 38 trap lines in an elevation range of 300 m to 4,200 m, which we binned into nine elevation zones. Each trap line had 50 Sherman traps run for 3–5 nights during 2003–05 and 2012–13. We had a total of 9,069 trap nights with 430 captures, including 13 species of murid rodents, five ground shrews, two voles, and one each of pika and tree shrews. The capture rate in a trap line ranged from 0 to 19.7 per 100 trap night (mean = 5.30±0.767 SEM) with a peak at 2,501–3,001 m (3.29±0.644), coinciding with temperate broad leaf and conifer forests. Species richness seemed to have a minor peak at 501–1,000 m (2.50±0.645 species per trapline) and a clear peak at 3,001–3,500 m (3.29±0.644), coinciding with tropical forests and temperate mixed conifer forests, respectively. The apparent bimodal elevation gradient is due to the overlap of western Asian and Indo-Malayan fauna in the lower elevation and of the latter and Palearctic fauna in the higher elevation. More intensive sampling is needed to test this hypothesis that the overlap of biogeographic regions can influence elevation gradient in species richness.

Breeding and population structure of the root vole <i>Alexandromys oeconomus</i> Pallas, 1776 (Cricetidae, Rodentia) in the Southern Trans-Urals region

Features of the breeding and population structure of the root vole inhabiting the Southern Trans-Urals region during the periods of 1981–2001 and 2020–2022 are considered. Animals were captured during both winter and snowless periods. A total of 754 root voles were captured using ditches with pitfalls (guide fences made of polyethylene film) and trap lines. As in the other parts of their range, root voles in the Southern Trans-Urals region prefer near-water habitats. Winter breeding is characteristic of this rodent in the Southern Trans-Urals region, but the most intensive breeding is observed in May–June. These months are also characterized by the maximum fecundity for both overwintered and young females. Overwintered females can produce up to 4 litters during their reproductive period, while young females can produce 3–4 litters. The fecundity of overwintered females is statistically significantly higher than that of young ones. In February–May, overwintered animals dominate in the root vole population, while in June and the following summer and autumn months, underyearlings predominate. Males dominate among the overwintered and underyearling animals; at the end of summer and in the autumn, the sex ratio among these age groups of root voles levels off.

Juan Modolell (1937-2023).

Juan Modolell (1937-2023).

Systematic analysis of YFP traps reveals common mRNA/protein discordance in neural tissues.

While post-transcriptional control is thought to be required at the periphery of neurons and glia, its extent is unclear. Here, we investigate systematically the spatial distribution and expression of mRNA at single molecule sensitivity and their corresponding proteins of 200 YFP trap lines across the intact Drosophila nervous system. 97.5% of the genes studied showed discordance between the distribution of mRNA and the proteins they encode in at least one region of the nervous system. These data suggest that post-transcriptional regulation is very common, helping to explain the complexity of the nervous system. We also discovered that 68.5% of these genes have transcripts present at the periphery of neurons, with 9.5% at the glial periphery. Peripheral transcripts include many potential new regulators of neurons, glia, and their interactions. Our approach is applicable to most genes and tissues and includes powerful novel data annotation and visualization tools for post-transcriptional regulation.

Acoustic telemetry informs conditional capture probability of an anadromous fish

Information on movement ecology and susceptibility to fishing gears is becoming increasingly employed in the management of commercial fisheries. This study combined acoustic telemetry (n = 51 and 52) and a simple passive integrated transponder (PIT) tag (n = 1499 and 1113) mark-recapture study, across two successive years on a commercial river lamprey (Lampetra fluviatilis) fishery, to inform exploitation rates and the influence of conditional capture probability on expected catch-per-unit-effort (CPUE). The movements of acoustic-tagged lamprey were used to refine estimates of the number of PIT-marked individuals vulnerable to the fishery. In 2018, this increased the recapture rate estimation by 0.99% and reduced the estimated run size by 152,101 (21.6%; 95% CL, 148,683, 155,688) individuals, with corresponding values of 0.12% and 114,639 (25.0%; 95% CL, 112,900, 116,448) in 2019. Lamprey movements were similar between years, with the number of trap line encounters by individuals between trap lifts used to inform expected CPUE for each lift. Conditional capture probability was mainly dependent on environmental conditions (e.g., river flow) with most trap lifts in the expected CPUE range, although the impacts of behaviour on vulnerability to capture were difficult to disentangle. This study highlights how the incorporation of acoustic telemetry increased the accuracy of, validated, and complemented mark-recapture data, without which management decisions (e.g., quota size) would have been based upon over 100,000 more individuals (27.5% higher than the adjusted run size in 2018 and 33.3% higher in 2019), with potentially severe consequences for the population. These findings demonstrate the importance of understanding fish movement to improve and inform fishery management. The study also presents a framework to quantify conditional capture probability and its influence on CPUE; knowledge that is widely applicable across aquatic systems for management and sustainability of fisheries.

Abundance and Condition of Populations of Small Mammals as Carriers of Natural Focal Human Diseases in the Karelia North-East Ladoga

Summing up the results of the long-term studies of population ecology and dynamics of small mammals for more than half a century (1966–2018). Small mammals are involved in the formation and functioning of natural-focil of human vector-borne diseases common in the North-Eastern Ladoga region. Encephalitis and tularemia circulate intensively in the Ladoga region under conditions of intensive anthropogenic transformation of taiga ecosystems. Local landscapes belong to the subzone of the middle taiga forests. Most of the studied species of small mammals are located in the northern periphery of this area. Here representatives of the native taiga fauna of Micromammalia constantly experience powerful anthropogenic pressure, which leads to a decrease in their abundance and correlation of the species. Of the total amount of 22 species of small mammals collected here, Sorex araneus and Myodes glareolus dominate. Next, the species prevalent (according to the degree of predominant species) in the counts are Microtus agrestis, Sorex minutus and Sorex caecutiens. Other species are relatively rare and appear in smaller numbers. Myodes glareolus has main role in the feeding of ticks and, accordingly, in the circulation of infections in nature, the differentiated contribution of individual intrapopulation groups in maintaining the number of vectors and the activity of pathogens. Shrews are important for the development of the larval stages of the tick. In the research area, were recorded total index of trap catch of abundance of small animals with trap lines from 0.34 to 18.5 individuals per 100 snap traps-nights (average of 7.8 ind.) and with pitfall traps recorded from 2.7 to 25.4 individuals per 10 ditch-nights (average of 14 ind.). This indicates that the studied area has smaller amount of mammals compared to other regions in Southern Europe. Nevertheless, the studies determine a rather tense epidemic situation in the studied area. Population of small mammals of boreal ecosystem steadily affect the mass feeding of carriers of natural focal infections.

Enhancer trap lines with GFP driven by smad6b and frizzled1 regulatory sequences for the study of epithelial morphogenesis in the developing zebrafish inner ear.

Live imaging in the zebrafish embryo using tissue-specific expression of fluorescent proteins can yield important insights into the mechanisms that drive sensory organ morphogenesis and cell differentiation. Morphogenesis of the semicircular canal ducts of the vertebrate inner ear requires a complex rearrangement of epithelial cells, including outgrowth, adhesion, fusion and perforation of epithelial projections to generate pillars of tissue that form the hubs of each canal. We report the insertion sites and expression patterns of two enhancer trap lines in the developing zebrafish embryo, each of which highlight different aspects of epithelial cell morphogenesis in the inner ear. A membrane-linked EGFP driven by smad6b regulatory sequences is expressed throughout the otic epithelium, most strongly on the lateral side of the ear and in the sensory cristae. A second enhancer trap line, with cytoplasmic EGFP driven by frizzled1 (fzd1) regulatory sequences, specifically marks cells of the ventral projection and pillar in the developing ear, and marginal cells in the sensory cristae, together with variable expression in the retina and epiphysis, and neurons elsewhere in the developing central nervous system. We have used a combination of methods to identify the insertion sites of these two transgenes, which were generated through random insertion, and show that Targeted Locus Amplification is a rapid and reliable method for the identification of insertion sites of randomly inserted transgenes.

On the formation of lines in quantum phase space

We theoretically study the formation of lines in phase space using Wigner’s distribution In trapped quantum systems such lines form generically, crisscrossing phase space and they can have astonishing extent, reaching across the entire state. In classical systems this does not happen. We show that the formation of such straight line patterns is due to the formation of ‘randomized comb-states’. We establish their stability to perturbations, and that they are tied to coherences in configuration space. We additionally identify generic higher-order ‘eye’ patterns in phase space which occur less often since they arise from more specific symmetric comb-states; we show that the perturbation of eye patterns through their randomization tends to deform them into lines. Lines in phase space should give rise to large probability peaks in measurements.