Larval clypeus shape provides an indicator for quantitative discrimination of species and larval stages in Japanese diving beetles Cybister (Coleoptera: Dytiscidae)

2021 ◽  
Author(s):  
Toshio Inoda ◽  
Kohei Watanabe ◽  
Tatsuki Odajima ◽  
Yusuke Miyazaki ◽  
Shintaro Yasui ◽  
...  
Keyword(s):  
Larval Stages ◽  
Diving Beetles

scholarly journals Food of adult diving beetles Colymbetes fuscus (Linnaeus, 1758) and C. striatus (Linnaeus, 1758) (Coleoptera: Dytiscidae) in the Zehlau Peatbog and in oxbow lakes and fens (the Biebrza Marshes)

2014 ◽  
Vol 83 (2) ◽  
pp. 171-180 ◽  
Author(s):  
Anna Frelik
Keyword(s):  
Aquatic Invertebrates ◽  
Beetle Species ◽  
Oxbow Lakes ◽  
Asellus Aquaticus ◽  
Aquatic Habitats ◽  
Gut Content ◽  
Larval Stages ◽  
Diving Beetles ◽  
Terrestrial Insects

AbstractThe study involved the analysis of the foregut content of 120 adult specimens of Colymbetes fuscus and C. striatus collected in aquatic habitats in the Biebrza Marshes (Poland) and the Zehlau Peatbog (Russia). The gut content comprised animals (including eggs of aquatic invertebrates), plants and detritus. Larvae of Ephemeroptera were common in beetles from the Biebrza Marshes. The gut content also included Dytiscidae, Cladocera, Chironomidae and other Diptera, Copepoda, other insects, other Coleoptera aquatica, Heteroptera, Acari, Ostracoda, Culicidae and Asellus aquaticus. In the Zehlau Peatbog, both of the beetle species fed predominantly on the larval stages of Chironomidae (Diptera). The gut content also included adult terrestrial insects and spiders.

A scanning electron microscopic study of the veliger larvae of the scallop argopecten purpuratus

1988 ◽  
Vol 46 ◽  
pp. 284-285
Author(s):  
G.C. Bellolio ◽  
K.S. Lohrmann ◽  
E.M. Dupré
Keyword(s):  
Morphological Description ◽  
Electron Microscopic ◽  
Larval Stages ◽  
Scanning Electron Microscopic Study ◽  
The Pacific ◽  
Argopecten Purpuratus ◽  
Veliger Larvae ◽  
20 Nm ◽  
Ethanol Series ◽  
Scanning Electron

Argopecten purpuratus is a scallop distributed in the Pacific coast of Chile and Peru. Although this species is mass cultured in both countries there is no morphological description available of the development of this bivalve except for few characterizations of some larval stages described for culture purposes. In this work veliger larvae (app. 140 pm length) were examined by the scanning electron microscope (SEM) in order to study some aspects of the organogenesis of this species.Veliger larvae were obtained from hatchery cultures, relaxed with a solution of MgCl2 and killed by slow addition of 21 glutaraldehyde (GA) in seawater (SW). They were fixed in 2% GA in calcium free artificial SW (pH 8.3), rinsed 3 times in calcium free SW, and dehydrated in a graded ethanol series. The larvae were critical point dried and mounted on double scotch tape (DST). To permit internal view, some valves were removed by slightly pressing and lifting the tip of a cactus spine wrapped with DST, The samples were coated with 20 nm gold and examined with a JEOL JSM T-300 operated at 15 KV.

Larval and juvenile development of the Iceland cockle Ciliatocardium ciliatum (Fabricius, 1780) (Bivalvia: Cardiidae)

2020 ◽  
Vol 324 (2) ◽  
pp. 242-251
Author(s):  
L.P. Flyachinskaya ◽  
P.A. Lezin
Keyword(s):  
Lateral Position ◽  
Larval Shell ◽  
Subtidal Zone ◽  
Larval Stages ◽  
Posterior Shoulder ◽  
Blade Shape ◽  
The Right ◽  
Lateral Structures ◽  
Juvenile Development ◽  
Concentric Structure

The paper considers the development of Ciliatocardium ciliatum from the stage of straight hinge to juvenile. In the White Sea the spawning of C. ciliatum begins at the end of June, larvae at different stages of development occur in plankton until the end of September. The earliest of the larvae found had shell lengths of 123–130 µm. The paper first examined the anatomy and structure of the larval shell of C. ciliatum. During the development, the main stages of organogenesis were described and special attention was paid to the formation of the digestive and muscular systems. The digestive system begins to function when the larva reaches a size of 170–180 µm. The digestive gland has a two-blade shape and is shifted to the right side. The foot is formed at a size of 230 µm, the gill rudiments appear when the larva reaches 270 µm. The development of the larval shell and larval hinge of the mollusc is considered in detail. The development of the larval shell of C. ciliatum is similar to the development of other family members. Throughout all the larval stages, the shell has a rounded shape with a low umbos, and the prodissoconch II has a clearly visible concentric structure. The C. ciliatum larval hinge is characterized by weak differentiation and the absence of pronounced cardinal teeth typical for other Cardiidae. However, the lateral structures of the castle – ridges and flanges – are well developed. The ligament begins to form at a size of 240–250 µm and occupies a lateral position. The settlement of the cockle takes place in September in the subtidal zone. After the metamorphosis, a large radial sculpture is formed on the dissoconch and a number of small spikes are formed at the rib of the posterior shoulder.

Further Problems in the Interpretation and Homology of the Insect Ovipositor

1964 ◽  
Vol 96 (1-2) ◽  
pp. 405-417 ◽  
Author(s):  
G. G. E. Scudder
Keyword(s):  
Experimental Study ◽  
Normal Development ◽  
Organ Formation ◽  
Larval Stages ◽  
Insect Phylogeny ◽  
Correct Form ◽  
Developmental Capacity ◽  
Mode Of Development ◽  
Dual Origin

AbstractAn attempt is made to re-evaluate the data on the origin of the ovipositor in insects and to explain its mode of development in living forms. Comparative developmental data from other groups of animals is cited to substantiate the claim that part of the insect ectodermal genitalia is appendicular rather than sternal in origin. It is suggested that the primary abdominal segmental appendages have provided a source of competent tissue which through subtle changes in selection, has evolved along many pathways, to form the gonocoxae, the pleuropodia, the pseudoplacenta and perhaps the prolegs in many different taxa.It is shown, by aid of sections through the insect embryo and larval stages, that the primary embryonic segmental appendages on the abdomen, do not differentiate; there is no loss of tissue and it cannot be proven that such appendages have been lost in insect phylogeny. The fact that they are represented still in the modern embryo, indicates that they have been retained. To explain the observable developmental details, it is suggested that abdominal limb histogenesis is arrested or suppressed in normal development, but this limb tissue retains its competence to differentiate. Thus development may be initiated again at a later time in postembryonic life. In this manner, the original limb tissue is available for organ formation in the maturing insect.The study has suggested that the appendages on the eighth and ninth segments of the abdomen initiate but do not complete their development in the polypod embryo. Possibly the potential limb tissue is arrested in development because it has not undergone some vital change as regards its capacity to respond (competence) to an inductor, perhaps the inductor is not available or perhaps it is not available in the correct form.There is evidence to suggest that the developmental capacity of the limb anlagen are reduced with time, so that full limb formation is not possible in postembryonic life: this can explain the development of abdominal coxae in the Thysanura and hence gonocoxae in higher insects. It is noted that should Gustafson's suggestion that the eversible sacs and gonapophyses are homologous with primary segmental genitalic ampullae prove acceptable, then the female ectodermal genitalia in insects would appear to have a dual origin.It is emphasized that the speculation expressed are being subjected to experimental study in an attempt to verify the suggested ontogeny and phylogeny.

scholarly journals Functional Characterization of the Adenylyl Cyclase Genesgs-1by Analysis of a Mutational Spectrum inCaenorhabditis elegans

Genetics ◽  
2002 ◽  
Vol 161 (1) ◽  
pp. 133-142 ◽  
Author(s):  
Celine Moorman ◽  
Ronald H A Plasterk
Keyword(s):  
Life Span ◽  
Adenylyl Cyclase ◽  
Neuronal Degeneration ◽  
Functional Characterization ◽  
Adenylyl Cyclases ◽  
Loss Of Function ◽  
C Elegans ◽  
Larval Stages ◽  
Pharyngeal Pumping

AbstractThe sgs-1 (suppressor of activated Gαs) gene encodes one of the four adenylyl cyclases in the nematode C. elegans and is most similar to mammalian adenylyl cyclase type IX. We isolated a complete loss-of-function mutation in sgs-1 and found it to result in animals with retarded development that arrest in variable larval stages. sgs-1 mutant animals exhibit lethargic movement and pharyngeal pumping and (while not reaching adulthood) have a mean life span that is >50% extended compared to wild type. An extensive set of reduction-of-function mutations in sgs-1 was isolated in a screen for suppressors of a neuronal degeneration phenotype induced by the expression of a constitutively active version of the heterotrimeric Gαs subunit of C. elegans. Although most of these mutations change conserved residues within the catalytic domains of sgs-1, mutations in the less-conserved transmembrane domains are also found. The sgs-1 reduction-of-function mutants are viable and have reduced locomotion rates, but do not show defects in pharyngeal pumping or life span.

Toxicity of petroleum hydrocarbons to Brachyuran crabs: a review of deleterious effects of oil-related xenobiotics on life stages

2021 ◽  
pp. 1-16
Author(s):  
Qusaie Karam ◽  
Zainab Al-Wazzan
Keyword(s):  
Petroleum Hydrocarbons ◽  
Marine Pollution ◽  
Human Consumption ◽  
Life Stages ◽  
Crab Species ◽  
Research Attention ◽  
Larval Stages ◽  
Effects Of Ph ◽  
Ph Toxicity ◽  
Brachyuran Crabs

Abstract Petroleum hydrocarbons (PH) toxicity and bioaccumulation in aquatic organisms have been investigated for almost 50 years. Continuous oil spillages necessitate a further understanding of the toxicological effects of PH on brachyuran crabs. Crabs can be exposed to PH through various routes such as the water column, sediment and diet. Numerous investigations have been dedicated to evaluating PH toxicity on different life stages of crab species, but the majority of them have focused on the blue crab Callinectes sapidus as it represents an edible and favourable seafood commodity for human consumption. The objective of the review is to critically assess studies related to PH toxicity on different life stages of 41 crab species representing 13 families across the world. Several physiological, biochemical and genetic endpoints of marine crabs were evaluated in addition to the sublethal effects of PH on crab metabolism, behaviour, moulting, growth and survival. A concise summary of PH deleterious effects on different taxonomic species of marine crabs is discussed and provides evidence that crabs can be used as indicator organisms of biomarker significance for marine pollution. Overall, larval stages appeared to be the most sensitive to the deleterious effects of PH compared with juveniles and adults. However, adult stages have received more research attention than other life stages, followed by larval stages, and juvenile stages are the least investigated stages with respect to PH toxicity. Finally, hepatopancreas and gills were the organs where greatest accumulation of PH was recorded.

Active prey selection in developing larvae of Atlantic bluefin tuna (Thunnus thynnus) in spawning grounds of the Gulf of Mexico

2021 ◽  
Author(s):  
Akihiro Shiroza ◽  
Estrella Malca ◽  
John T Lamkin ◽  
Trika Gerard ◽  
Michael R Landry ◽  
...  
Keyword(s):  
Gulf Of Mexico ◽  
Prey Selection ◽  
Bluefin Tuna ◽  
Gut Contents ◽  
Physical Factors ◽  
Larval Rearing ◽  
Thunnus Thynnus ◽  
Small Copepod ◽  
Atlantic Bluefin Tuna ◽  
Larval Stages

Abstract Bluefin tuna spawn in restricted areas of subtropical oligotrophic seas. Here, we investigate the zooplankton prey and feeding selectivity of early larval stages of Atlantic bluefin tuna (ABT, Thunnus thynnus) in larval rearing habitat of the Gulf of Mexico. Larvae and zooplankton were collected during two multi-day Lagrangian experiments during peak spawning in May 2017 and 2018. Larvae were categorized by flexion stage and standard length. We identified, enumerated and sized zooplankton from larval gut contents and in the ambient community. Ciliates were quantitatively important (up to 9%) in carbon-based diets of early larvae. As larvae grew, diet composition and prey selection shifted from small copepod nauplii and calanoid copepodites to larger podonid cladocerans, which accounted for up to 70% of ingested carbon. Even when cladoceran abundances were <0.2 m−3, they comprised 23% of postflexion stage diet. Feeding behaviors of larvae at different development stages were more specialized, and prey selection narrowed to appendicularians and primarily cladocerans when these taxa were more abundant. Our findings suggest that ABT larvae have the capacity to switch from passive selection, regulated by physical factors, to active selection of presumably energetically optimal prey.

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

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.

scholarly journals RNA-Seq reveals divergent gene expression between larvae with contrasting trophic modes in the poecilogonous polychaete Boccardia wellingtonensis

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Álvaro Figueroa ◽  
Antonio Brante ◽  
Leyla Cárdenas
Keyword(s):  
De Novo ◽  
Juvenile Stage ◽  
Type I ◽  
Rna Seq ◽  
Mrna Synthesis ◽  
De Novo Transcriptome ◽  
Larval Stages ◽  
Divergent Gene ◽  
Genetic Mechanisms ◽  
Planktotrophic Larvae

AbstractThe polychaete Boccardia wellingtonensis is a poecilogonous species that produces different larval types. Females may lay Type I capsules, in which only planktotrophic larvae are present, or Type III capsules that contain planktotrophic and adelphophagic larvae as well as nurse eggs. While planktotrophic larvae do not feed during encapsulation, adelphophagic larvae develop by feeding on nurse eggs and on other larvae inside the capsules and hatch at the juvenile stage. Previous works have not found differences in the morphology between the two larval types; thus, the factors explaining contrasting feeding abilities in larvae of this species are still unknown. In this paper, we use a transcriptomic approach to study the cellular and genetic mechanisms underlying the different larval trophic modes of B. wellingtonensis. By using approximately 624 million high-quality reads, we assemble the de novo transcriptome with 133,314 contigs, coding 32,390 putative proteins. We identify 5221 genes that are up-regulated in larval stages compared to their expression in adult individuals. The genetic expression profile differed between larval trophic modes, with genes involved in lipid metabolism and chaetogenesis over expressed in planktotrophic larvae. In contrast, up-regulated genes in adelphophagic larvae were associated with DNA replication and mRNA synthesis.

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