Stages Of Postembryonic Development Research Articles

Pseudoescorpiones (Arachnida: Pseudoscorpiones) asociados con vertederos de Atta colombica (Guérin-Méneville, 1844) (Hymenoptera: Formicidae) en Panamá

Waste heaps of Atta are host to an extraordinary diversity of myrmecophiles insects and other arthropods. In this study, the presence of four species of pseudoscorpions is recorded in two Atta colombica waste heaps in the years 2016 and 2017. Two of these species, Cordylochernes scorpioides and Lustrochernes carolinensis are new records in waste heaps and except for the deutonymphs of L.carolinensis, the others all stages of post-embryonic development were present in the studied heaps, which could indicate that these two species carry out their entire life cycle in these waste mounds and live there permanently.

EFFECT OF COMBINATED APPLICATION OF PROBIOTIC AND ENTEROSORBENT ON THE DYNAMICS OF CORTISOL IN CHICKENS IN THE EARLY POSTEMBRIONIC PERIOD

The research is devoted to the study of chickens’ cortisol dynamics at an early stage ofpost-embryonic development with the use of probiotics such as zoonorm, enterosorbent based on polymethylsilxane polyhydrate and their complex. To achieve the goal, 4 groups of analogue chickens were formed, 1 was a control group, 2 - received a probiotic in a mixture with feed at a dose of 0.2 g per head in morning feeding; 3 - 0.3% weight enterosorbent 2 hours after evening feeding; 4 - a combination of two preparations at the appropriate time. The introduction of drugs was carried out from 5- to 25-day age. All the indicators were analyzed in 5-, 15-, 25- and 35-day chicks. As a result of the research, chicks in all groups showed an increase in cortisol concentrations. In the control group a stable growth of the indicator was observed, which reached a maximum in 35 days, an increase in the concentration of the hormone by 41.6% was accompanied by an increase in glucose to 14.6 to 0.5 mmol/L, a decrease in cholesterol and triglycerides. In chicks 2 and 3 groups the highest value of cortisol is noted in 25 days, 4 - in 15 days. In 2 and 3 groups, with maximum cortisol levels, glucose concentrations were 14.64 and 14.91 mmol/L, with a marked decrease in triglycerides and cholesterol. In the 4th group of 15-day-old chicks, an 8.4% increase in cholesterol and triglycerides resulted in a 37.3 and 68.9% decrease in cholesterol and triglycerides. At the end of the experiment, the 4th group was found to reduce cortisol to 5.07 nmol/L, glucose to 12.32 to 0.13 mmol/L, and a relative increase in triglycerides. In conclusion, the relationship between synthesis of cortisol, cholesterol, triglycerides, glucose and their metabolism was confirmed. There has been a marked reduction in the influence of stress factors and increased resistance of chickens with the complex use of probiotic and enterosorbent.

Olfactory epithelium ontogenesis and function in postembryonic North American Bullfrog (Rana(Lithobates)catesbeiana) tadpoles

During metamorphosis, the olfactory system remodelling in anuran tadpoles — to transition from detecting waterborne odorants to volatile odorants as frogs — is extensive. How the olfactory system transitions from the larval to frog form is poorly understood, particularly in species that become (semi-)terrestrial. We investigated the ontogeny and function of the olfactory epithelium of North American Bullfrog (Rana (Lithobates) catesbeiana Shaw, 1802) tadpoles at various stages of postembryonic development. Changes in sensory components observable at the epithelial surface were examined by scanning electron microscopy. Functionality of the developing epithelium was tested using a neurophysiological technique (electro-olfactography (EOG)), and behaviourally, using a choice maze to assess tadpole response to olfactory stimuli (algae extract, amino acids). The youngest (premetamorphic) tadpoles responded behaviourally to an amino acid mixture despite having underdeveloped olfactory structures (cilia, olfactory knobs) and no EOG response. The consistent appearance of olfactory structures in older (prometamorphic) tadpoles coincided with reliably obtaining EOG responses to olfactory stimuli. However, as tadpoles aged further, and despite indistinguishable differences in sensory components, behavioural- and EOG-based olfactory responses were drastically reduced, most strongly near metamorphic climax. This work demonstrates a more complex relationship between structure and function of the olfactory system during tadpole life history than originally thought.

Automated Platform for Long-Term Culture and High-Content Phenotyping of Single C. elegans Worms

The nematode Caenorhabditis elegans is a suitable model organism in drug screening. Traditionally worms are grown on agar plates, posing many challenges for long-term culture and phenotyping of animals under identical conditions. Microfluidics allows for ‘personalized’ phenotyping, as microfluidic chips permit collecting individual responses over worms’ full life. Here, we present a multiplexed, high-throughput, high-resolution microfluidic approach to culture C. elegans from embryo to the adult stage at single animal resolution. We allocated single embryos to growth chambers, for observing the main embryonic and post-embryonic development stages and phenotypes, while exposing worms to up to 8 different well-controlled chemical conditions. Our approach allowed eliminating bacteria aggregation and biofilm formation-related clogging issues, which enabled us performing up to 80 hours of automated single worm culture studies. Our microfluidic platform is linked with an automated phenotyping code that registers organism-associated phenotypes at high-throughput. We validated our platform with a dose-response study of the anthelmintic drug tetramisole by studying its influence through the life cycle of the nematodes. In parallel, we could observe development effects and variations in single embryo and worm viability due to the bleaching procedure that is standardly used for harvesting the embryos from a worm culture agar plate.

Differences in firing efficiency, chromatin, and transcription underlie the developmental plasticity of the Arabidopsis DNA replication origins.

Eukaryotic genome replication depends on thousands of DNA replication origins (ORIs). A major challenge is to learn ORI biology in multicellular organisms in the context of growing organs to understand their developmental plasticity. We have identified a set of ORIs of Arabidopsis thaliana and their chromatin landscape at two stages of post-embryonic development. ORIs associate with multiple chromatin signatures including transcription start sites (TSS) but also proximal and distal regulatory regions and heterochromatin, where ORIs colocalize with retrotransposons. In addition, quantitative analysis of ORI activity led us to conclude that strong ORIs have high GC content and clusters of GGN trinucleotides. Development primarily influences ORI firing strength rather than ORI location. ORIs that preferentially fire at early developmental stages colocalize with GC-rich heterochromatin, but at later stages with transcribed genes, perhaps as a consequence of changes in chromatin features associated with developmental processes. Our study provides the set of ORIs active in an organism at the post-embryo stage that should allow us to study ORI biology in response to development, environment, and mutations with a quantitative approach. In a wider scope, the computational strategies developed here can be transferred to other eukaryotic systems.

Bioenergetic Health Assessment of a Single Caenorhabditis elegans from Postembryonic Development to Aging Stages via Monitoring Changes in the Oxygen Consumption Rate within a Microfluidic Device.

Monitoring dynamic changes in oxygen consumption rates (OCR) of a living organism in real time provide an indirect method of monitoring changes in mitochondrial function during development, aging, or malfunctioning processes. In this study, we developed a microfluidic device integrated with an optical detection system to measure the OCR of a single developing Caenorhabditis elegans (C. elegans) from postembryonic development to aging stages in real time via phase-based phosphorescence lifetime measurement. The device consists of two components: an acrylic microwell deposited with an oxygen-sensitive luminescent layer for oxygen (O2) measurement and a microfluidic module with a pneumatically driven acrylic lid to controllably seal the microwell. We successfully measured the basal respiration (basal OCR, in pmol O2/min/worm) of a single C. elegans inside a microwell from the stages of postembryonic development (larval stages) through adulthood to aged adult. Sequentially adding metabolic inhibitors to block bioenergetic pathways allowed us to measure the metabolic profiles of a single C. elegans at key growth and aging stages, determining the following fundamental parameters: basal OCR, adenosine triphosphate (ATP)-linked OCR, maximal OCR, reserve respiratory capacity, OCR due to proton leak, and non-mitochondrial OCR. The bioenergetic health index (BHI) was calculated from these fundamental parameters to assess the bioenergetic health of a single developing C. elegans from the postembryonic development to aging stages. The changes in BHI are correlated to C. elegans development stage, with the highest BHI = 27.5 for 4-day-old adults, which possess well-developed bioenergetic functionality. Our proposed platform demonstrates for the first time the feasibility of assessing the BHI of a single C. elegans from postembryonic development to aging stages inside a microfluidic device and provides the potential for a wide variety of biomedical applications that relate mitochondrial malfunction and diseases.

Hematopoietic activity of rat bone marrow at the influence of salt extract of Hirudo verbana Carena, 1820

The mitotic activity of the bone marrow of non-linear female rats after feeding their offspring was studied and this index was estimated in their offspring in the early stages of postembryonic development – on the 1, 15, 30, 45, 60th day. Females two weeks prior to mating with males and two weeks after were intraperitoneally injected with Hirudo verbana saline extract (5 mg/kg of the weight of an animal), once, every week. In the experimental group of females, the mitotic index significantly increased (by 33.61%); in their offspring, the maximum increase in the mitotic index was observed on the first day (by 50.88%); the increase in the proliferative activity of bone marrow cells was observed at other observation times: on the 30th day (by 25.67%) and on the 60th day (by 18.35%). In the experimental group of animals, all hematopoietic parameters of peripheral blood (the number of leukocytes, erythrocytes, hemoglobin) also increased. An increase in the number of leukocytes in the experimental group of females occurred without significant changes in their relative population ratios in the leukocyte blood formula. In the experimental group of the offspring, the effect of the leech extract on the changes in the differentiation of leukocyte populations was revealed. Thus, in the offspring for the first day the shift of the leukocyte blood formula to the left decreased due to the decrease in cells of innate immunity (granulocytes and monocytes) and increase in adaptive immunity cells (lymphocytes), which indicates an accelerated differentiation of the lymphoid system towards adult animals. Some differences in the differentiation of leukocytes were noted at the onset of sexual maturation (on the 30th day) and at its end (on the 60th day). At these times, a neutrophilic shift occurred to the left, as a consequence of the intension of the congenital link of immunity in the presence of an adequate number of cells of adaptive immunity. Thus, as a result of the study, the stimulating effect of the extract of the medical leech on the mitotic activity of the bone marrow was revealed, both in mature females and in their offspring, which resulted in an increase in the number of leukocytes, erythrocytes, hemoglobin, and color index. In the offspring, during the period of increased stress of morphogenesis, there is an activation of both the congenital and adaptive links of immunity in the experimental group of animals.

Проліферативна активність лімфоцитів крові нелінійних самиць щурів, їх приплоду на ранніх етапах постембріонального розвитку на фоні гірудовпливу

Проліферативна активність лімфоцитів крові нелінійних самиць щурів, їх приплоду на ранніх етапах постембріонального розвитку на фоні гірудовпливу

The early Cambrian fossil embryo Pseudooides is a direct-developing cnidarian, not an early ecdysozoan.

Early Cambrian Pseudooides prima has been described from embryonic and post-embryonic stages of development, exhibiting long germ-band development. There has been some debate about the pattern of segmentation, but this interpretation, as among the earliest records of ecdysozoans, has been generally accepted. Here, we show that the ‘germ band’ of P. prima embryos separates along its mid axis during development, with the transverse furrows between the ‘somites’ unfolding into the polar aperture of the ten-sided theca of Hexaconularia sichuanensis, conventionally interpreted as a scyphozoan cnidarian; co-occurring post-embryonic remains of ecdysozoans are unrelated. We recognize H. sichuanensis as a junior synonym of P. prima as a consequence of identifying these two form-taxa as distinct developmental stages of the same organism. Direct development in P. prima parallels the co-occuring olivooids Olivooides, and Quadrapyrgites and Bayesian phylogenetic analysis of a novel phenotype dataset indicates that, despite differences in their tetra-, penta- and pseudo-hexa-radial symmetry, these hexangulaconulariids comprise a clade of scyphozoan medusozoans, with Arthrochites and conulariids, that all exhibit direct development from embryo to thecate polyp. The affinity of hexangulaconulariids and olivooids to extant scyphozoan medusozoans indicates that the prevalence of tetraradial symmetry and indirect development are a vestige of a broader spectrum of body-plan symmetries and developmental modes that was manifest in their early Phanerozoic counterparts.

Phagocytic and metabolic activity of neutrophils of rats in the early stages of post-embryonic development under the influence of biologically active substances of the salt extract of Hirudo verbana

The nitroblue tetrazolium test reflects the degree of activation of oxygen-dependent mechanisms of bactericidal activity of phagocytotic cells, so the increase in nbt-test and phagocytic indices shows increased activation in the bacterial process and enhanced protection with the help of the absorption ability of the cells in the body. We examined females of nonlinear rats after feeding of their offspring, which 2 weeks before and 2 weeks after mating were injected intraperitoneally with antigens of saline extract of medical leeches (4 injections) and the offspring at days 1, 15, 30, 45, 60. The dosage of salt extract antigens was carried out by determining the protein concentrations using the Lowry protein assay. The animals were immobilized using an immobilizing device. The animals were distributed into three groups: the first research and experimental group of animals was subject to the influence of medical leech salt extract antigens to the amount of 0.5 ml (at the rate of 3 µg/g of animal weight); the second group of intact animals was not subject to intervention, the third control group of animals was administered intraperitoneally saline 0.5 ml of 9% saline solution. We studied females after feeding offspring and offspring at 1, 15, 30, 60 days. The animals were kept in vivarium conditions in individual cages on a standard diet. In the experiment we used 60 females of non-linear rats and 300 of their offspring. All animals were decapitated under ether anesthesia. After that, we took blood, made a solution with crystal heparin and examined the laboratory parameters: total number of leukocytes and leukocyte formula. Evaluation of nonspecific resistance of the organism was investigated using tests which characterize the activity of neutrophils (nbt-test, phagocytosis indices). The results of our studies revealed a positive effect of antigens of saline extract of medical leeches on the absorptive and metabolic activity of neutrophils in the females and their offspring in all study periods compared with the control, an increased number of leukocytes, due to the change of the process of differentiation and deposition of cells in immunogenic organs on proliferation. Changes in immunological parameters indicate the immunostimulatory effect of AG ML on leukopoiesis and on the functional activity of neutrophils – the first line of defense against entry into the body of a variety of bacteria, fungi and protozoa.

THE ACTIVITY OF LYSOSOMAL NUCLEASES IN DIFFERENT AGE GROUPS OF SALMON SALMO SALAR L.

At present time, due to the deterioration of environment, the pollution of rivers by industrial and domestic wastewater, as well as unsustainable fishing resulted in decrease of Atlantic salmon reserves all over the world. In the north-west part of Russia, the one of few rivers where the natural reproduction of this the most valuable commercial species is preserved, is Varzuga River (Murmansk region). To develop strategies for sustainable conservation of salmon populations the monitoring should be conducted in order to maintain stable living conditions in the river ecosystem. It is known that the enzymes involved in the protein, energy and carbohydrate metabolism are quite informative indicators of fish growth, development and adaptation to environmental changes. Along with parameters mentioned above, lysosomal hydrolyses, including acid nucleases involved in compensatory reconstructions of nucleic acid and the closely related protein metabolism are used to assess the status of aquatic ecosystems. The activity of lysosomal nucleases (RNAse, DNAse) in muscles of different age groups (0+, 1+, 2+) of juvenile Atlantic salmon Salmo salar L. from Varzuga River (Sobachiy porog) was investigated in the present study. It was shown that the activity of enzymes studied and the protein content in skeletal muscles increased linearly and were maximal in two-years-old salmon. The absolute values of lysosomal RNAse activity were slightly higher than DNAse activity. The data obtained indicate that the active participation of lysosomal nucleases in adaptive reactions of juvenile salmon on the early stages of post-embryonic development. First of all, it results in the intensification of biosynthetic processes of protein. To conclude the living conditions in Varzuga River are favorable for the growth and development of juvenile Atlantic salmon.

Morphological abnormalities in pike Esox lucius at early stages of postembryonic development

Morphological abnormalities in prolarvae of pike Esox lucius have been studied; data on their occurrence are provided. Among revealed disturbances, great partial occurrence is accounted for by abnormalities of the yolk sac and body curvature.

Spatiotemporal sequestration of miR165/166 by Arabidopsis Argonaute10 promotes shoot apical meristem maintenance.

Arabidopsis Argonaute10 (AGO10) specifically sequesters miR165 and miR166 and antagonizes their activity, thus regulating shoot apical meristem (SAM) development. However, where and when this sequestration acts is currently unclear. We show here that AGO10 represses miR165/166 activity in the embryo proper during early embryogenesis, through the apical and central regions of mature embryos, and eventually in the entire adaxial domain and vasculature of the cotyledons and leaf primordia. These locations are essentially identical to regions expressing PHABULOSA and REVOLUTA, mRNA targets of miR165/166. The Arabidopsis genome contains nine MIR165/166 genes. Sequestration of miR165/166 by the MIR165b, MIR166a, MIR166b, and MIR166g promoters efficiently rescues the SAM defect in ago10 mutants. Comparison of the expression patterns of AGO10 and the four MIR165/166 members suggests that AGO10 quenches the non-cell-autonomous activity of any miR165/166 that moves into AGO10-expressing niches. Thus, this study provides insight into how the spatiotemporal regulation of AGO10-miR165/166 activity affects SAM development.

Comparative ultrastructure of the terminal portions of the male copulatory apparatus in Planorbidae (Gastropoda: Pulmonata)

Terminal portions of the male copulatory apparatus of Planorbis planorbis, Segmentina oelandica, and Anisus vortex were studied using whole-mount preparations, serial semi-thin sections, and transmission electron microscopy. In the latter species, stylet formation was investigated at several stages of postembryonic development. Organization of the penial distal portion in the species studied varies greatly. In P. planorbis, the distal end of the penis lacks developed papillae and is armed with a stylet built up of the covering epithelial cells of the penis proper. In A. vortex, the stylet is formed by the secretory activity of the middle cells of the distal portion of the penis. To the time of maturation, the cells encompassing the stylet are broken down exposing its solid chitinous structure and characteristic shape. In S. oelandica, the distal end of the penis bears the long probably flexible papilla with the characteristics of an internal ‘skeleton,’ organized as a line of connective tissue cells and a system of hydrocoelic cavities.

Species identification at the larval and juvenile stages for several Chinese domestic fishes by elliptical Fourier analysis of otolith form

The sagitta morphological development of laboratory cultured Hypophthalmichthys molitrix,Aristich-thys nobilis,and Ctenopharyngodon idellus during the postembryonic development stage was studied.Stepwise discriminant analysis was used to distinguish these three species based on the day ages after hatching,sagitta shapes,postembryonic development stages and different body length groups by elliptical Fourier analysis of oto-lith morphology.The results showed that the total classification success(%) all increased gradually.The classifi-cation success was 79.79% on the fourth day after hatching,above 90% on the tenth day after hatching,and up to 100% after 18 days.The classification success was below 90% before the chordal tip lifting stage and above 95% after the two chamber air bladder stage.According to the sagitta morphology,the classification success at round and near round stages was 61% and 81%,respectively,but was over 90% after the oval stage.The classification success based on different body length groups was initially over 90%.So,if only compared by classification suc-cess,the approach based on different body length groups performed the best.The approach based on sagitta mor-phology and postembryonic development stages was more general in use.

Observations on morphology of post-embryonic development and histology of sensory organs in larval and juvenile Siberian sturgeon, Acipenser baerii

Siberian sturgeon,Acipenser baerii,one of the oldest extant cold-water fish species in the world,are of considerable research and economic value.We documented the postembryonic development of the Siberian stur-geon by monitoring morphological characteristics and cell types in retina,taste buds,olfactory sac,and ampullary organs in the larvae.The stages of postembryonic development were defined based on both the external morphol-ogy and the internal organ characteristics.Larvae were reared at a water temperature of(18.0±1.0)℃ and a pH of 7.0?7.5.The newly hatched larvae(day 0) were(9.05±0.14) mm long.During the early-stages of development(days 0–7),the larvae were nurtured by a large yolk sac and the eye was the primary sense organ.The late-stage larvae(day 8?–22) were characterized by the disappearance of the yolk sac and initiation of active feeding,the formation of fins and fin rays,a shift in habitat use towards the bottom of the water column,and the completion of organ differentiation.As larvae reached the juvenile stage(day 23–57),the scutes begin to form,the organs tended to become fully developed,and the external morphology and body color pattern gradually matured into the adult pattern.We observed some differences in the development characteristics of the primary sensory organs in Sibe-rian sturgeon relative to other teleosts.Our observations suggest that Siberian sturgeon is an ancient species that occupy a unique position during the evolution of teleosts.

Fertility: Role of Repressor of Estrogen Receptor Activity

Uterine adenogenesis, a unique postnatal event in mammals, refers to morphological differentiation and development of the uterus that is vulnerable to adverse effects of endocrine disrupters (1). Key morphogenetic events in uterine adenogenesis include 1) organization and stratification of stromal cells, 2) differentiation and growth of the myometrium, and 3) differentiation and morphogenesis of the uterine glands (1, 2). Progressive development of uterine luminal epithelium (LE) gives rise to buds that transition to glandular epithelium (GE) followed by tubulogenesis and coiling and branching morphogenesis to form mature uterine glands (see Fig. 1). Uterine adenogenesis is disrupted by inappropriate exposure of the neonatal lamb to either estradiol-17 or progesterone between postnatal day (PND) 0 and PND 56 (2) resulting in an aglandular uterus. Exposure of the neonatal mouse to progesterone between PND 3 and PND 9 also abrogates uterine adenogenesis (3). Disruption of uterine adenogenesis in both ewes and mice results in infertility. The effectiveness of nuclear hormone-receptor complexes depends on coregulator partner proteins, some of which affect uterine development and fertility. The importance of the coregulator designated repressor of estrogen receptor activity (REA) in uterine adenogenesis has been clarified through research of collaborating scientists at the University of Illinois and Baylor College of Medicine (4).Globaldeletionof theREAgenewas embryonic lethal; therefore, REA was conditionally deleted only in cells that express progesterone receptors to determine effects on postembryonic stages of development in mice. Mice conditionally homozygous for deletion of REA (REAd/d) developed to adulthood and had normal ovarian function but were infertile due to disruption of uterine adenogenesis resulting in the absence of uterine glands and failure of implantation and endometrial decidualization. However, mice heterozygous for REA (REAf/d) were hyperresponsive to estradiol-17 as evidenced by increased proliferation of uterine LE and enhanced fluid imbibition associated with altered expression of aquaporin genes. Park et al. (4) concluded that uterine development and regulation of estrogen receptor activities have a bimodal dependence on gene dosage of REA. There was normal uterine development and function in wild-type mice, whereas partial deletion of REA (REAf/d) resulted in uterine hyperresponsiveness and subfertility, and complete deletion of REA (REAd/d) abrogated uterine adenogenesis and fertility. Uterine adenogenesis also fails in mice lacking functional genes required for interactions between epithelium and stroma including Wnt7a (5), Wnt5a (6), Foxa2 (7), a member of the forkhead transcription factor family, and E-cadherin (Cdh1) (8). Hormonal regulation of Cdh1 in uteri of mice is not known, but expression of Wnt7a, Wnt5a, and Foxa2 genes is affected by sex steroids (7, 9). At birth, uteri of mice and rats consist of uterine LE supported by undifferentiated mesenchyme (10). On PND 5, epithelial invaginations form buds for development of uterine GE and developed GE are present on PND 7 and 9 in mice and rats, respectively (11). In rats, uterine adenogenesis proceeds from PND 9 through PND 15, resulting in development of simple, tubular, and slightly coiled uterine glands (11). Interestingly, Park et al. (4) found the altered uterine phenotype in REAd/d mice between PND 10 and 14, the period of development of uterine glands.

In vivo analyses of the roles of essential Omp85-related proteins in the chloroplast outer envelope membrane.

Two different, essential Omp85 (Outer membrane protein, 85 kD)-related proteins exist in the outer envelope membrane of Arabidopsis (Arabidopsis thaliana) chloroplasts: Toc75 (Translocon at the outer envelope membrane of chloroplasts, 75 kD), encoded by atTOC75-III; and OEP80 (Outer Envelope Protein, 80 kD), encoded by AtOEP80/atTOC75-V. The atToc75-III protein is closely related to the originally identified pea (Pisum sativum) Toc75 protein, and it forms a preprotein translocation channel during chloroplast import; the AtOEP80 protein is considerably more divergent from pea Toc75, and its role is unknown. As knockout mutations for atTOC75-III and AtOEP80 are embryo lethal, we employed a dexamethasone-inducible RNA interference strategy (using the pOpOff2 vector) to conduct in vivo studies on the roles of these two proteins in older, postembryonic plants. We conducted comparative studies on plants silenced for atToc75-III (atToc75-III↓) or AtOEP80 (AtOEP80↓), as well as additional studies on a stable, atToc75-III missense allele (toc75-III-3/modifier of altered response to gravity1), and our results indicated that both proteins are important for chloroplast biogenesis at postembryonic stages of development. Moreover, both are important for photosynthetic and nonphotosynthetic development, albeit to different degrees: atToc75-III↓ phenotypes were considerably more severe than those of AtOEP80↓. Qualitative similarity between the atToc75-III↓ and AtOEP80↓ phenotypes may be linked to deficiencies in atToc75-III and other TOC proteins in AtOEP80↓ plants. Detailed analysis of atToc75-III↓ plants, by electron microscopy, immunoblotting, quantitative proteomics, and protein import assays, indicated that these plants are defective in relation to the biogenesis of both photosynthetic and nonphotosynthetic plastids and preproteins, confirming the earlier hypothesis that atToc75-III functions promiscuously in different substrate-specific import pathways.

Illumination controls differentiation of dopamine neurons regulating behaviour

Specification of the appropriate neurotransmitter is a crucial step in neuronal differentiation because it enables signalling among populations of neurons. Experimental manipulations demonstrate that both autonomous and activity-dependent genetic programs contribute to this process during development, but whether natural environmental stimuli specify transmitter expression in a neuronal population is unknown. We investigated neurons of the ventral suprachiasmatic nucleus that regulate neuroendocrine pituitary function in response to light in teleosts, amphibia and primates. Here we show that altering light exposure, which changes the sensory input to the circuit controlling adaptation of skin pigmentation to background, changes the number of neurons expressing dopamine in larvae of the amphibian Xenopus laevis in a circuit-specific and activity-dependent manner. Neurons newly expressing dopamine then regulate changes in camouflage colouration in response to illumination. Thus, physiological activity alters the numbers of behaviourally relevant amine-transmitter-expressing neurons in the brain at postembryonic stages of development. The results may be pertinent to changes in cognitive states that are regulated by biogenic amines.

Esterase profile in the postembryonic development of Rhipicephalusmicroplus

The objective of this work was to analyze the pattern of esterase activity in the development stages of Rhipicephalus microplus by nondenaturing polyacrylamide gel electrophoresis using specific staining for esterase. The electrophoretical results revealed the presence of nine regions displaying esterase activity, stained with both alpha-naphthyl acetate and beta-naphthyl acetate, and classified as alpha-beta-esterase. Stage-specific esterases were found, with the first nymphal and larval stages showing the greatest esterase activity throughout the development. An esterase called EST-4 was detected only in males and was considered sex-specific. There are differences in the esterase profile among the different postembryonic development stages of R. microplus.