Search results for "Ontogeny"

Ontogeny of the Calliandra – massulae (Mimosaceae: Ingeae), and the associated viscin body

2006

Abstract Polyads, called also massulae, are common in the Mimosaceae. Within this family, only in Calliandra (s. l.) polyads show a remarkable morphological variation: 16-grained lens-shaped massulae in the neotropical Zapoteca (syn. Calliandra p.p.), and highly asymmetric eight-grained massulae in Calliandra (s. str.). As a further specialisation the massulae in Calliandra (s. str.) possess a sticky appendage called a viscin body. The form and ontogeny of this unique two-dimensional construction of the massula is of particular interest. In Calliandra (s. str.) the octad is normally the developmental product of the initiation stage, beginning with one pollen mother cell (PMC). In total, Cal…

Ontogeny of Heterocypris bosniaca (Ostracoda: Cyprididae): description of postembryonic instars and rediscovery of the neglected A-9 stage

2013

Despite being the most common and widespread family of Ostracoda in fresh water, the Cyprididae are still poorly known with respect to species ontogeny. The full series of eight juvenile instars has been described in detail for just five of the approximately 1000 living species, and only in one case did this include the earliest A-9 stage. We aimed to fill this gap with a morphological study of the post-embryonic development of Heterocypris bosniaca Petkowski, Scharf and Keyser, 2000, a species with unusual morphological traits within the genus, including putatively paedomorphic characters such as valves without tubercles and the narrow calcified inner lamella on both valves. Inside the egg…

Evolution Within a Bizarre Phylum: Homologies of the First Echinoderms

1998

SYNOPSIS. The Extraxial/Axial Theory (EAT) of echinoderm skeletal homologies describes two major body wall types: axial and extraxial. The latter is subdivided into perforate and imperforate regions. Each of the regions has a distinctly different source in early larval development. Axial skeleton originates in the rudiment, and develops in association with the pentaradially arranged hydrocoel according to specific ontogenetic principles. Perforate and imperforate extraxial regions are associated with the left and right somatocoels respectively, are not governed by ontogenetic principles of plate addition, and are products of the non-rudiment part of the larval body. The morphology of even t…

Dietary ontogeny and niche shift to piscivory in lacustrine brown trout Salmo trutta revealed by stomach content and stable isotope analyses

2012

The feeding ecology and ontogeny of a large size range of brown trout Salmo trutta in Lake Fyresvatnet, southern Norway, were examined by stomach content and stable isotope analyses. According to the stomach contents, the S. trutta changed their diet at c. 30 cm total length (L(T) ). The smaller size classes fed on benthic invertebrates and surface insects, whereas larger S. trutta (30 cm) fed mainly on whitefish Coregonus lavaretus. A similar, but more gradual shift to piscivory in the size range 25-30 cm was found when using the stable isotope mixing model SIAR to reveal dietary ontogeny. The δ¹³C isotopic signature confirmed that S. trutta independent of size predominantly relied upon be…

Ontogenetic development of the holocephalan dentition: Morphological transitions of dentine in the absence of teeth.

2021

Among the cartilaginous fishes (Chondrichthyes), the Holocephali are unique in that teeth are absent both in ontogeny and adult regenerative growth. Instead, the holocephalan dentition of ever-growing nonshedding dental plates is composed of dentine, trabecular in arrangement, forming spaces into which a novel hypermineralized dentine (whitlockin) is deposited. These tissue features form a variety of specific morphologies as the defining characters of dental plates in the three families of extant holocephalans. We demonstrate how this morphology changes through ontogenetic development with continuity between morphologies, through successive growth stages of the dentition represented by the …

Thalamic Network Oscillations Synchronize Ontogenetic Columns in the Newborn Rat Barrel Cortex

2013

Neocortical areas are organized in columns, which form the basic structural and functional modules of intracortical information processing. Using voltage-sensitive dye imaging and simultaneous multi-channel extracellular recordings in the barrel cortex of newborn rats in vivo, we found that spontaneously occurring and whisker stimulation-induced gamma bursts followed by longer lasting spindle bursts were topographically organized in functional cortical columns already at the day of birth. Gamma bursts synchronized a cortical network of 300-400 µm in diameter and were coherent with gamma activity recorded simultaneously in the thalamic ventral posterior medial (VPM) nucleus. Cortical gamma b…

1993

We may state that the path of development of an organism can play an important role in its immediate realization and also in its possible transformation. This leads to the problem of the existence of a causative link between individual development (ontogeny) and evolutionary history (phylogeny). This problem which has been dealt with by numerous authors, has led to contradictory answers, depending on the direction of the supposed connection: from the evolutionary history to individual development or vice versa, that is, from individual development to the evolutionary history.

Influence of Temperature, Hypercapnia, and Development on the Relative Expression of Different Hemocyanin Isoforms in the Common CuttlefishSepia offi…

2012

The cuttlefish Sepia officinalis expresses several hemocyanin isoforms with potentially different pH optima, indicating their reliance on efficient pH regulation in the blood. Ongoing ocean warming and acidification could influence the oxygen-binding properties of respiratory pigments in ectothermic marine invertebrates. This study examined whether S. officinalis differentially expresses individual hemocyanin isoforms to maintain optimal oxygen transport during development and acclimation to elevated seawater pCO2 and temperature. Using quantitative PCR, we measured relative mRNA expression levels of three different hemocyanin isoforms in several ontogenetic stages (embryos, hatchlings, juv…

Tectogonotoechia rivasi n. sp. A new lower Pragian Celtiberian (Spain) Ancystrorhynchoidea rhynchonellid brachiopod

2020

A new lower Pragian Ancystrorhynchoidea rhynchonellid, Tectogonotoechia rivasi n. sp. of the Celtiberian region (Eastern Iberian Chain, EIC, and Eastern Guadarrama, EG) is described and figured. The growth of the new species, from the last neanic stage to the senescent one is specially underlined. T. rivasi n. sp. is characterized as the other species of the genus by the occurrence of a pseudoseptum and a pseudoseptalium in the dorsal interior, with a fine connectivum forming a roofed over structure covering most part of the latter. Exteriorly, the species is an entirely costate, strongly dorsibiconvex, uniplicate form lacking of marginal spines. T. rivasi n. sp. is fairly abundant in the u…

DEVELOPMENTAL ASPECTS OF DRUG METABOLISM

1977

Publisher Summary This chapter discusses the developmental aspects of drug metabolism and those of other biological phenomena that are twofold. Development is described by examining various species of different levels of biological evolution or by studying the ontogenetic evolvement of the features in question in one animal species or groups of related species. A review on diene-organochlorine insecticides epitomizes the fact that insects, birds, and fish possess the enzymatic mechanisms for epoxidation of these insecticides to only a slightly less degree than do mammals. Thus, the ability to oxidize foreign compounds does not seem to be restricted to animals of higher organization, and con…