Evaluation of Effective and Practical Euthanasia Methods for Larval African Clawed Frogs (Xenopus laevis)

Larval, or tadpole-stage Xenopus laevis frogs are a popular research model for developmental biology and disease studies. Existing euthanasia guidance documents offer recommendations for both eggs and adult stages, yet do not specifically address the larval stage. Data evaluating effective euthanasia methods for groups of X. laevis tadpoles would therefore be useful. The goal of the current study was to evaluate the efficacy of various immersion euthanasia procedures on tadpoles: tricaine methanesulfonate (MS222) at 6 g/L, eugenol at 800 μL/L and rapid chilling (2 to 4 °C). We also evaluated tadpoles at various developmental stages (NF stages 46, 47 and 49). Tadpoles (n = 70) were exposed to euthanasia solution for 15 min, and controls (n = 40) were placed in housing tank water for 15 min. All animals were then placed in recovery tanks containing housing tank water for 4 h to confirm irreversibility of each agent. Cessation of the heartbeat was assessed at the end of euthanasia solution exposure and at each hour thereafter. We found that immersion in a 6 g/L solution of MS222 resulted in 100% euthanasia of all larval stages tested. Conversely, eugenol produced variable euthanasia rates that were affected by both age group and batches of stock solutions. Rapid chilling was completely ineffective as a euthanasia method in our study. Based on our findings, we recommend MS222 as an effective and practical means of euthanizing large numbers of X. laevis tadpoles.

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LABORATORY STUDIES ON THE TOXICITY OF INSECTICIDES TO THE BERTHA ARMYWORM (MAMESTRA CONFIGURATA) (LEPIDOPTERA: NOCTUIDAE)

The Canadian Entomologist ◽

10.4039/ent107865-8 ◽

1975 ◽

Vol 107 (8) ◽

pp. 865-872 ◽

Cited By ~ 1

Author(s):

C. R. Harris ◽

S.A. Turnbull

Keyword(s):

Direct Contact ◽

Developmental Stages ◽

Contact Toxicity ◽

Mamestra Configurata ◽

Larval Stages ◽

Large Numbers ◽

Third Stage ◽

History Of ◽

Dual Objectives ◽

Bertha Armyworm

AbstractThis study had dual objectives: to select a series of insecticides toxic to the bertha armyworm, Mamestra configurata (Walk.), and to determine susceptibility of the various developmental stages to insecticides. Pupae were collected from infested rapeseed fields in Alberta and a laboratory rearing procedure suitable for production of large numbers of insects was devised. The direct contact toxicity of 50 insecticides to third-stage larvae was assessed. Methomyl and DDT were included as standard insecticides. None of the experimental insecticides was as toxic as methomyl but about one half were more toxic than DDT. Tests with representative organochlorine, organophosphorus, and carbamate insecticides indicated that all caused rapid knockdown of third-stage larvae. There was no evidence of subsequent recovery. After the life history of the bertha armyworm under controlled environmental conditions was determined, tests were conducted to ascertain the susceptibility of the various developmental stages to methomyl, chlorpyrifos, leptophos, and methidathion. Eggs and first and second stage larvae were more susceptible to direct contact applications of the insecticides than were the later larval stages, pupae, and adults.

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Expression of intermediate filament proteins during development of Xenopus laevis. III. Identification of mRNAs encoding cytokeratins typical of complex epithelia

Development ◽

10.1242/dev.104.4.533 ◽

1988 ◽

Vol 104 (4) ◽

pp. 533-548 ◽

Cited By ~ 1

Author(s):

B. Fouquet ◽

H. Herrmann ◽

J.K. Franz ◽

W.W. Franke

Keyword(s):

Xenopus Laevis ◽

Developmental Stages ◽

Type I ◽

Type Ii ◽

S1 Nuclease ◽

Intermediate Filament Proteins ◽

Larval Stages ◽

Adult Tissues ◽

Adult Organism ◽

Restricted Pattern

A Xenopus laevis mRNA encoding a cytokeratin of the basic (type II) subfamily that is expressed in postgastrulation embryos was cDNA-cloned and sequenced. Comparison of the deduced amino acid sequence of this polypeptide (513 residues, calculated mol. wt 55,454; Mr approximately 58,000 on SDS-PAGE) with those of other cytokeratins revealed its relationship to certain type II cytokeratins of the same and other species, but also remarkable differences. Using a subclone representing the 3′-untranslated portion of the 2.4 kb mRNA encoding this cytokeratin, designated XenCK55(5/6), in Northern blot experiments, we found that it differs from the only other Xenopus type II cytokeratin known, i.e. the simple epithelium-type component XenCK1(8), in that it is absent in unfertilized eggs and pregastrulation embryos. XenCK55(5/6) mRNA was first detected at gastrulation (stage 11) and found to rapidly increase during neurulation and further development. It was also identified in Xenopus laevis cultured kidney epithelial cells of the line A6 and in the adult animal where it is a major polypeptide in the oesophageal mucosa but absent in most other tissues examined. The pattern of XenCK55(5/6) expression during embryonic development was similar to that reported for the type I polypeptides of the ‘XK81 subfamily’ previously reported to be embryo-specific and absent in adult tissues. Therefore, we used a XK81 mRNA probe representing the 3′-untranslated region in Northern blots, S1 nuclease and hybrid-selection-translation assays and found the approximately 1.6 kb XK81 mRNA and the resulting protein of Mr approximately 48,000 not only in postgastrula embryos and tadpoles but also in the oesophagus of adult animals. Our results show that both these type II and type I cytokeratins are synthesized only on gastrulation and are very actively produced in early developmental stages but is continued in at least one epithelium of the adult organism. These observations raise doubts on the occurrence of Xenopus cytokeratins that are strictly specific for certain embryonic or larval stages and absent in the adult. They rather suggest that embryonically expressed cytokeratins are also produced in some adult tissues, although in a restricted pattern of tissue and cell type distribution.

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Platyhelminths from the South African Clawed Toad, or Platanna (Xenopus laevis)

Journal of Helminthology ◽

10.1017/s0022149x00023890 ◽

1973 ◽

Vol 47 (2) ◽

pp. 199-235 ◽

Cited By ~ 14

Author(s):

William Macnae ◽

Liebe Rock ◽

Matthew Makowski

Keyword(s):

Xenopus Laevis ◽

South African ◽

Large Scale ◽

Developmental Stages ◽

First Year ◽

Pericardial Cavity ◽

Large Numbers ◽

South African Universities ◽

In Captivity ◽

Large Scale Survey

Since the discovery by Shapiro and Zwarenstein (1934) that females of Xenopus laevis (Daudin, 1802) respond to hormones present in the urine of pregnant women, this species of amphibian has proved to be a useful experimental animal. It is easily kept in captivity and can be reared through all its developmental stages without difficulty.This species, the clawed toad or platanna, is commonly used in South African Universities as a type for first year dissection. This has given the opportunity to check large numbers of specimens for the more obvious parasites, i.e. those which live in the gallbladder, the urinary bladder, the peritoneal cavity and the pericardial cavity. A similar large scale survey of intraintestinal parasites has not been feasible, although many alimentary canals have been searched for parasites.

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Development of Testis Cords and the Formation of Efferent Ducts in Xenopus laevis: Differences and Similarities with Other Vertebrates

Sexual Development ◽

10.1159/000513416 ◽

2021 ◽

pp. 1-14

Author(s):

Yuanyuan Li ◽

Jinbo Li ◽

Man Cai ◽

Zhanfen Qin

Keyword(s):

Cell Proliferation ◽

Xenopus Laevis ◽

Germ Cells ◽

Sertoli Cells ◽

Testis Development ◽

Larval Stages ◽

Efferent Ducts ◽

Steroidogenic Cells ◽

Testis Cord ◽

Anterior Posterior

The knowledge of testis development in amphibians relative to amniotes remains limited. Here, we used Xenopus laevis to investigate the process of testis cord development. Morphological observations revealed the presence of segmental gonomeres consisting of medullary knots in male gonads at stages 52–53, with no distinct gonomeres in female gonads. Further observations showed that cell proliferation occurs at specific sites along the anterior-posterior axis of the future testis at stage 50, which contributes to the formation of medullary knots. At stage 53, adjacent gonomeres become close to each other, resulting in fusion; then (pre-)Sertoli cells aggregate and form primitive testis cords, which ultimately become testis cords when germ cells are present inside. The process of testis cord formation in X. laevis appears to be more complex than in amniotes. Strikingly, steroidogenic cells appear earlier than (pre-)Sertoli cells in differentiating testes of X. laevis, which differs from earlier differentiation of (pre-)Sertoli cells in amniotes. Importantly, we found that the mesonephros is connected to the testis gonomere at a specific site at early larval stages and that these connections become efferent ducts after metamorphosis, which challenges the previous concept that the mesonephric side and the gonadal side initially develop in isolation and then connect to each other in amphibians and amniotes.

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Seasonal occurrence of some larval stages of endoparasites in three cyprinids from the Nwanedi-Luphephe dams, the Limpopo River System, South Africa

Helminthologia ◽

10.1515/helmin-2015-0037 ◽

2015 ◽

Vol 52 (3) ◽

pp. 229-235 ◽

Cited By ~ 2

Author(s):

E. M. Mbokane ◽

J. Theron ◽

W. J. Luus-Powell

Keyword(s):

Developmental Stages ◽

River System ◽

Intestinal Wall ◽

The Body ◽

Seasonal Occurrence ◽

Seasonal Fluctuations ◽

Metazoan Parasites ◽

Larval Stages ◽

Parasite Communities ◽

Third Stage

Abstract This study provides information on seasonal occurrence of developmental stages of endoparasites infecting three cyprinids in the Nwanedi-Luphephe dams, Limpopo River System. Labeobarbus marequensis (Smith, 1841), Barbus trimaculatus Peters, 1852 and Barbus radiatus Peters, 1853 were investigated seasonally from January 2008 to October 2008. The following larvae of metazoan parasites were collected: Diplostomum sp. from the eyes of L. marequensis and B. trimaculatus; Ornithodiplostomum sp. from the gills of B. trimaculatus; Posthodiplostomum sp. from muscle, skin and fins of B. trimaculatus and B. radiatus; third-stage Contracaecum larvae (L3) from the mesentery fats and on the liver lobes of L. marequensis and B. trimaculatus and gryporynchid cestode larvae from the outer intestinal wall of B. radiatus. All the flukes encountered were metacercariae. Diplostomum sp. and Contracaecum sp. dominated the parasite communities. Their prevalence exhibited seasonal fluctuations with maxima in summer. Factors likely to influence fish infection such as the body size of fish and their condition factors were also briefly considered in this study.

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A size threshold governs Caenorhabditis elegans developmental progression

Proceedings of The Royal Society B Biological Sciences ◽

10.1098/rspb.2015.1283 ◽

2015 ◽

Vol 282 (1813) ◽

pp. 20151283 ◽

Cited By ~ 22

Author(s):

Sravanti Uppaluri ◽

Clifford P. Brangwynne

Keyword(s):

Caenorhabditis Elegans ◽

Food Availability ◽

Developmental Stages ◽

Size Control ◽

Threshold Size ◽

Larval Stages ◽

Developmental Progression ◽

Order Of Magnitude ◽

Size Threshold ◽

The Impact

The growth of organisms from humans to bacteria is affected by environmental conditions. However, mechanisms governing growth and size control are not well understood, particularly in the context of changes in food availability in developing multicellular organisms. Here, we use a novel microfluidic platform to study the impact of diet on the growth and development of the nematode Caenorhabditis elegans . This device allows us to observe individual worms throughout larval development, quantify their growth as well as pinpoint the moulting transitions marking successive developmental stages. Under conditions of low food availability, worms grow very slowly, but do not moult until they have achieved a threshold size. The time spent in larval stages can be extended by over an order of magnitude, in agreement with a simple threshold size model. Thus, a critical worm size appears to trigger developmental progression, and may contribute to prolonged lifespan under dietary restriction.

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The biology of Limacina retroversa

Journal of the Marine Biological Association of the United Kingdom ◽

10.1017/s002531540000833x ◽

1954 ◽

Vol 33 (2) ◽

pp. 297-312 ◽

Cited By ~ 37

Author(s):

J. E. Morton

Keyword(s):

Life History ◽

Breeding Season ◽

Detailed Account ◽

Larval Stages ◽

Large Numbers ◽

History Of ◽

Clione Limacina

The Plymouth Fauna List contains records of two genera of pteropods, Limacina and Clione. Of the first, Limacina retroversa (Flem.) is by far the better-known species, apparently occurring regularly at Plymouth in large numbers in townettings from outside, and sometimes inside, the Sound. It breeds at Plymouth from June to August, and Lebour (1932) has given a detailed account of its breeding and larval stages and has discussed its role in the plankton. The second species of Limacina at Plymouth is lesueuri (d'Orbigny), which has been observed from time to time since 1906, when it was very common. The last record in the Fauna is off the Breakwater in 1920. Of the gymnosomatous pteropods, Clione limacina Phipps is the only species regularly occurring. Lebour (1931) has described the life history of this form, and mentions February to August as its months of greatest abundance. Its breeding season is June to August. Another gymnosome, tentatively referred to as Clionina longicauda, is reported by Russell (1936), and from the specimen department at Plymouth Laboratory the writer obtained some preserved specimens, not easily identifiable, of a Pneumodermopsis taken locally; its species is perhaps ciliata, recorded by Massy (1917) from the Irish Coast.

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The distribution of E-cadherin during Xenopus laevis development

Development ◽

10.1242/dev.111.1.159 ◽

1991 ◽

Vol 111 (1) ◽

pp. 159-169 ◽

Cited By ~ 2

Author(s):

G. Levi ◽

B. Gumbiner ◽

J.P. Thiery

Keyword(s):

Xenopus Laevis ◽

Developmental Stages ◽

Early Embryo ◽

The Body ◽

Gut Epithelium ◽

A Cell ◽

Well Differentiated ◽

Sensory Layer ◽

Endodermal Cells ◽

E Cadherin

A vast amount of experimental evidence suggests that cell surface molecules involved in cell-to-cell and/or cell-to-substrate interactions participate in the control of basic events in morphogenesis. E-cadherin is a cell adhesion molecule directly implicated in the control of Ca2(+)-dependent interactions between epithelial cells. We report here the patterns of expression of E-cadherin in developmental stages of Xenopus laevis ranging from early embryo to adult using immunofluorescence microscopy. Although its distribution shares some similarities with those of L-CAM in the chicken and E-cadherin/Uvomorulin in the mouse, the distribution of E-cadherin in Xenopus presents several peculiar and unique features. In early stages of Xenopus development, E-cadherin is not expressed. The molecule is first detectable in the ectoderm of late gastrulas (stage 13-13.5 NF). At this time both the external and the sensory layer of the nonneural ectoderm accumulate high levels of E-cadherin while the ectoderm overlying the neural plate and regions of the involuting marginal zone (IMZ) not yet internalized by the movements of gastrulation are E-cadherin-negative. Unlike most other species, endodermal cells express no or very low levels of E-cadherin up to stage 20 NF. Endodermal cells become strongly E-cadherin-positive only when a well-differentiated epithelium forms in the gut. No mesodermal structures are stained during early development. In the placodes, in contrast to other species, E-cadherin disappears very rapidly after placode thickening. During further embryonic development E-cadherin is present in the skin, the gut epithelium, the pancreas, many monostratified epithelia and most glands. Hepatocytes are stained weakly while most other tissues, including the pronephros, are negative. In the mesonephros, the Wolffian duct and some tubules are positive. During metamorphosis a profound restructuring of the body plan takes place under the control of thyroid hormones, which involves the degeneration and subsequent regeneration of several tissues such as the skin and the gut. All newly formed epithelia express high levels of E-cadherin. Surprisingly, degenerating epithelia of both skin and intestine maintain high levels of the protein even after starting to become disorganized and to degenerate. In the adult, staining is strong in the skin, the glands, the lungs, the gut epithelium and the pancreas, weak in the liver and absent from most other tissues. Our results show that the expression of E-cadherin in Xenopus is strongly correlated with the appearance of differentiated epithelia.

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Observations on Scale Production in Pyramimonas Amylifera Conrad

Journal of Cell Science ◽

10.1242/jcs.1.4.429 ◽

1966 ◽

Vol 1 (4) ◽

pp. 429-438

Author(s):

IRENE MANTON

Keyword(s):

Developmental Stages ◽

Basic Problem ◽

Scale Production ◽

Body Type ◽

Primary Object ◽

Large Numbers ◽

Golgi Structure ◽

Flagellar Scales ◽

Duct Opening ◽

Narrow Duct

Scale production has been studied after glutaraldehyde fixation with the primary object of tracing the source of flagellar scales which this species is known to possess (Manton, Oates & Parke, 1963). Large numbers of all types of flagellar scales, unmixed with body-type scales, are detectable at all times, stored in an orderly arrangement within a vesicular scale reservoir of characteristic morphology which is described. These scales are liberated through a narrow duct opening to the cell exterior near the flagellar bases. This duct is thought to be temporary and subject to reformation with minor change of site, since open ducts are more frequently encountered in darkness than by day; some putative developmental stages are illustrated. Observations on other details of scale production include demonstration of the formation of all types of body scales within the Golgi cisternae, sometimes together with a few flagella-type scales. The larger body-type scales are uniformly oriented within the Golgi cisternae in relation to the position of the subtending endoplasmic reticulum. This orientation is lost before liberation to the cell surface, which occurs from moderate-sized detached vesicles in an unknown manner. The implications of these findings for an understanding of Golgi structure and of the basic problem of scale arrangement on the receiving sites are discussed in a preliminary way.

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Factors involved in the development of ipsilateral retinothalamic projections in Xenopus laevis

Development ◽

10.1242/dev.65.1.199 ◽

1981 ◽

Vol 65 (1) ◽

pp. 199-217

Author(s):

C. Kennard

Keyword(s):

Visual Field ◽

Xenopus Laevis ◽

Visual Information ◽

Experimental Manipulation ◽

Larval Life ◽

Optic Chiasma ◽

Larval Stages ◽

Ipsilateral Projection ◽

Terminal Degeneration ◽

Selective Pattern

The extent, and the development, of the ipsilateral retinothalamic projection in the frog Xenopus laevis have been studied using terminal degeneration and autoradiographic techniques. This ipsilateral projection derives only from those retinal areas receiving visual information from the binocular portion of the visual field. In Xenopus, the ipsilateral retinothalamic projection arises from a larger area of the retina than was found to be the case in earlier studies on Rana. This correlates with the fact that Xenopus has a larger binocular visual field than does Rana. The ipsilateral retinothalamic projection is just detectable at about stage 56 of larval life, considerably later than its contralateral counterpart. Experimental manipulation of the developing eye vesicle at early larval stages followed by histological studies of the ipsilateral retinothalamic projections showed, however, that the retinal areas which give rise to this projection are determined by stage 32 of larval life. Further studies, in which monocular enucleation was performed at different larval stages with subsequent examination of the retinothalamic projections from the remaining eye, indicated that the selective pattern of decussation and non-decussation of retinothalamic fibres at the optic chiasma does not require interactions, at the chiasma, between optic fibres from the two eyes.

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