bluuebunny/crossref_metadata_2025_split huggingface dataset:
Cell Cycle
Authors: Stein Gary S , Medina Ricardo , van Wijnen André J , Stein Janet L , Lian Jane B , Owen Thomas A 
Published: April 2013

Abstract

Competency for proliferation and cell cycle progression are governed by complex and interdependent processes that support DNA replication and mitotic division. Genetic and epigenetic controls are operative. The architectural organisation of the regulatory machinery for gene expression is compartmentalised in microenvironments of interphase nucleus and at gene loci on mitotic chromosomes. The cell cycle requires selective expression of genes that encode cell cycle regulatory proteins. A broad spectrum of signalling mechanisms integrate and amplify growth‐related regulatory cues that mediate fidelity of cell cycle control. There are unique requirements for cell cycle control to support the rapid proliferation that occurs during initial stages of embryogenesis and continued renewal of stem cell populations. The cell cycle regulatory mechanisms that are compromised in cancer cells provide insight into control of transformation and tumourigenesis as well as serve as targets for therapy.

Key Concepts:

Competency for proliferation and cell cycle progression requires selective expression of genes that encode cell cycle regulatory proteins.

Transcriptional and post‐transcriptional mechanisms mediate control of the cell cycle.

Genetic and epigenetic mechanisms support cell cycle progression.

The regulatory machinery for gene expression that supports cell cycle control is architecturally organised and assembled in nuclear microenvironments.

Unique mechanisms govern control of proliferation during early embryogenesis and for renewal of stem cell populations.

Regulatory parameters of cell cycle control that are compromised in cancer cells serve as a platform for tumour diagnosis and therapy.

Synchronisation of cell cycle progression supports identification of cell cycle regulatory parameters and mechanisms that are compromised in transformed and tumour cells.

Regulatory mechanisms that control the cell cycle in yeast have provided valuable insight into cell cycle control in mammalian cells.
Tunicate Embryos and Cell Specification
Authors: Satoh Noriyuki 
Published: April 2013

AbstractTunicates are marine invertebrate chordates and closest relatives of vertebrates. The most common tunicates are ascidians. The fertilised egg of ascidians develops quickly into a tadpole‐type larva. The larva is composed of approximately 2600 cells and has distinct organs including the nervous system, endoderm and mesenchyme in the trunk, and muscle and notochord in the tail. The larval surface is covered by an epidermis. This configuration represents a basic body plan of chordates. Every blastomere of early embryos up to the gastrula stage is distinguishable, and invariant lineage of embryonic cells is well documented. Cell fate restriction occurs relatively early in ascidian embryos. Maternal factors are responsible for differentiation of muscle, endoderm and epidermis, whereas the notochord and nervous system are specified by cellular interactions. Genes that are involved in the specification of embryonic cells have been identified. The tunicate is an emerging model for studies of embryonic cell specification.Key Concepts:In ascidians, invariant lineage of embryonic cells is completely described up to the gastrula stage.Developmental fates of most embryonic cells are determined during the blastula formation.Maternal factors are responsible for differentiation of muscle, endoderm and epidermis.The notochord and nervous system are specified by cellular interactions.Genes that are responsible for the specification of embryonic cells have been identified.The tunicate is an emerging model for studies of embryonic cell specification.
Diversity of Life
Authors: Minelli Alessandro , Bonato Lucio 
Published: April 2013

Abstract

Diversity of life (also called biological diversity or biodiversity) is the variety of living systems. It may refer to extant organisms, but also to their diversity in the past. It is usually meant to encompass multiple levels of biological systems, from the gene level, through the level of populations and species, up to the communities of organisms and the ecosystems to which they belong. Habitat fragmentation and host specialisation are two of the major causes explaining the origin of the multiplication of living species in the course of evolutionary history. About 2 million species have been described to date and some 17 000–19 000 new entries are added every year to this list. The number of living species existing on Earth is unknown, current estimates favouring figures in the range of 8–12 millions.

Key Concepts:

There are three major ranks of biological diversity on Earth, at the gene, species and ecosystem level respectively.

Species diversity is fostered mainly by geographical isolation and by strict interspecific relationships such as parasitism, food specialisation and plant pollination by insects.

All animal phyla are represented in the sea and several phyla including echinoderms, ctenophores and brachiopods are exclusively marine, but only 15% of all living species described to date inhabit the sea.

Insects represent more than one half of the total species‐level biological diversity on Earth.

Key events in the history of life were the Cambrian ‘explosion’ and the invasion of land by plants (Middle Silurian), arthropods (Upper Silurian) and vertebrates (Upper Devonian).

The history of biological diversity was punctuated by major critical events (mass extinctions) of which the most severe marks the end of the Palaeozoic era.

Recent descriptions of previously unknown species include a few cetaceans and other large animals as well as small animals representing completely new classes or phyla, such as Loricifera, Cicliophora and Micrognathozoa.

A sensible approach to estimating the number of existing species is to compare the number of described and undescribed species collected by prolonged sampling efforts in biologically rich and hitherto less investigated areas.

Global estimates of existing biodiversity range from 5 to 130 million species, a figure of 8–12 millions being currently favoured.
Phylogeny and Stratigraphy Comparison
Authors: Wagner Peter 
Published: April 2013

AbstractPhylogenetic relationships among taxa can be estimated in a number of ways. Given known fossil records, phylogenetic estimates implicitly hypothesise the latest possible origination times of taxa. One can use these inferences as models to evaluate the quality of the fossil record. Originally, it was hoped that these metrics would obviate the need for probabilistic models. However, subsequent research shows that all these metrics are affected by the same factors affecting probabilistic models while also being highly sensitive to the accuracy of the model phylogeny. Alternatively, one can treat these inferences as hypotheses to be tested by stratigraphic distribution data. Given the sensitivity of phylogenetic inference to ideas about character evolution and levels of convergence, this offers a promising avenue for reducing untested assumptions yielding initial phylogenetic estimates.Key Concepts:Particular ideas about phylogenetic relationships have implications about both macroevolutionary models and preservation models.There are several ways to describe gaps implied by inferred phylogenies, but all reflect factors other than simple preservation rate, especially the accuracy of the phylogeny.Using stratigraphic data to test phylogenetic inferences as hypotheses might help assess the assumptions underlying phylogenetic inference.
Old World Monkeys
Authors: Frost Stephen R , Rosenberger Alfred L , Hartwig Walter C 
Published: April 2013

Abstract

Old World monkeys, or cercopithecoids, are a diverse and widespread group of primates found throughout Africa and Asia. They are characterised by their specialised molar teeth, quadrupedal running behaviour, often spending more time on the ground than other primates, as well as their often large and complex social groups. They survive in the widest range of habitats of any nonhuman primates, with some species restricted to humid tropical forests whereas others are found in mountains and deserts. There are two main groups: the cercopithecines, which have cheek‐pouches and include macaques, baboons, mangabeys, vervets and guenons; and the colobines, characterised by complex stomach anatomy that allows them to digest leaves and which include langurs, proboscis monkeys, doucs and snub‐nosed monkeys and colobus monkeys. Although they are termed ‘monkeys’ they are more closely related to apes and humans (hominoids) than they are to the monkeys of Central and South America.

Key Concepts:

As they are large, occur in large social groups, are often terrestrial and active during the day, Old World monkeys are some of the most thoroughly studied wild primates.

Groups of closely related females, called matrilines, usually form the core of Old World monkey social groups because females remain in the same group as their mothers, whereas males generally transfer to a new group when they become adults.

Old World monkeys are the most diverse group of primates in terms of environmental and geographic range, as well as number of species, but have achieved this diversity through relatively narrow morphological and behavioural adaptations that allow for ecological flexibility.

Compared to other primate groups, Old World monkeys are a recent adaptive radiation, which may in part explain their relative lack of anatomical diversity, and they seem to have replaced the apes as the predominant primates in Africa and Eurasia as climatic change made environments more open and seasonal.
Nematomorpha (Horsehair Worms)
Authors: Poinar George 
Published: April 2013

Abstract

The phylum Nematomorpha, the hairworms, occurs worldwide. All members are developmental parasites of aquatic or terrestrial invertebrates. One genus,
Nectonema
, is marine, whereas the remaining species occur in freshwater as free‐living stages or inside terrestrial hosts. Hairworms have two or more hosts in their life cycle. The first paratenic host is just a carrier to the second developmental host. In the developmental host, the hairworm grows to maturity and often kills the host upon emergence. There is no direct economic or medical importance of hairworms and while they can reach up to a foot in length, they are rarely seen. A few species may effect populations of herbivorous insects, but most are not important as biological control agents. Most freshwater hairworms are threatened from polluted waters, habitat displacement and reduced host populations. Many could be considered as candidates for the Red Data Book of rare and endangered species. Hairworms are a relict group that is not closely related to any other living phylum. The preparasitic larvae are quite different from the adults since they possess spines for entering the body cavity of paratenic hosts. Once inside the paratenic host, the larva is surrounded by host tissue and is known as an ‘encysted’ larva. It remains in the cyst until the paratenic host is ingested by a suitable developmental host. If the second host is not suitable for development, the hairworm larvae can encyst again in the new paratenic host.

Key Concepts:

Hairworms are becoming endangered in many areas of the world.

Hairworms have attracted the attention of behaviourists who study how these parasites control the movements of their hosts.

Hairworms have no direct economic or medical importance.

Hairworms have the ability to arrest development in nondevelopmental hosts.

Hairworms are an enigmatic group that are not closely related to any other invertebrates.

Hairworms are an ancient group, with fossils dating back to the Early Cretaceous.
Acanthocephala
Authors: Richardson DJ 
Published: April 2013

Abstract

The phylum Acanthocephala is comprised of more than 1000 species of pseudoceolomic helminths, which, as adults, occur exclusively in the vertebrate small intestine. The most commonly parasitised definitive hosts are bony fishes, followed by birds, mammals and rarely amphibians and reptiles. Acanthocephalans are characterised by the possession of a head called a proboscis bearing hooks and spines that enable them to attach to the intestinal wall of their definitive host. Acanthocephalans are dioecious and exhibit sexual dimorphism. As an adaptation to parasitism, acanthocephalans have secondarily lost their digestive system and acquire their nutrients by direct absorption across the body wall. Acanthocephalans are primarily osmoconformers, and respiration and excretion occur primarily by diffusion across the body wall. All acanthocephalans exhibit an indirect life cycle utilising an arthropod intermediate host. Despite their sometimes large size, acanthocephalans cause relatively little pathology. Although very rare, human infection does occur. Molecular evidence suggests that Acanthocephalans are phylogenetically most closely aligned with the rotifers.

Key Concepts:

As adults, acanthocephalans are parasites of vertebrates.

Acanthocephalans have secondarily lost their digestive system as an adaptation to parasitism.

Acanthocephalans are closely related to the rotifers.

Approximately 1200 species of acanthocephalans have been described.

Acanthocephalans get their name from the spiny head called a proboscis.
Arthropoda (Arthropods)
Authors: Blackstone Neil W 
Published: April 2013

AbstractThe Arthropoda is a phylum of ecdysozoan animals in which the epidermis produces a segmented, jointed and hardened exoskeleton, which has internal musculature. Each segment primitively bears a pair of jointed limbs. Limbs may be uniramous (one branched) or biramous (two branched). Segments tend to be grouped into body regions or tagmata. Each major group of arthropods is characterised by a particular tagmosis. Arthropods include groups that are wholly marine (the extinct trilobites); marine, terrestrial and freshwater (chelicerates and crustaceans); terrestrial and freshwater (insects) or exclusively terrestrial (myriapods). Arthropods exhibit unparalleled diversity and abundance along with a correspondingly large ecological impact. Recent phylogenomic studies are beginning to resolve arthropod relationships. Two of the largest groups of arthropods – crustaceans and insects – form a single clade, the Pancrustacea. A group containing remipede crustaceans is sister to insects. The Mandibulata (Pancrustacea and Myriapoda) is well supported, and the Oligostraca exhibit a sister‐group relationship to all other pancrustaceans.Key Concepts:Arthropods are characterised by a segmented, jointed and hardened exoskeleton that has internal musculature.Major groups of arthropods exhibit a characteristic tagmosis.Arthropods include trilobites, chelicerates, crustaceans, insects and myriapods.Many arthropods have compound eyes.Arthropod limbs may be uniramous (one branched) or biramous (two branched).Arthropods include the only invertebrate group to evolve flight.Arthropods are both extremely diverse and highly abundant.The Pancrustacea includes the crustaceans and insects.A group containing remipede crustaceans exhibits a sister‐group relationship to insects.The Mandibulata includes the pancrustaceans and myriapods.
Crustacea (Crustaceans)
Authors: Blackstone Neil W 
Published: April 2013

Abstract

The Crustacea is a subphylum of arthropods defined by the nauplius larva, two pairs of antennae and biramous (‘two branched’) second antennae. Other limbs are biramous as well, and the body includes an abdomen, a thorax and a five‐segmented head. Mandibles and other specialised feeding appendages are present. The gut is lined with a cuticle that is molted along with the exoskeleton. A haemocoel and a dorsal, ostiate heart are present. Nephridial excretory organs may be specialised as antennal or maxillary glands. Crustaceans exhibit an incredible diversity and abundance, ranging from tiny planktonic or interstitial forms less than a millimetre in length to much larger forms, including shrimp, lobsters and crabs. An abundant fossil record is found, extending back to the Burgess Shale. Crustacean phylogeny has recently been roiled by the ‘pancrustacean hypothesis’: insects and crustaceans form one large clade. As traditionally viewed, crustaceans are thus very likely paraphyletic.

Key Concepts:

Crustaceans share several derived features: the nauplius larva, two pairs of antennae and biramous (‘two branched’) second antennae.

Crustaceans exhibit an abdomen, a thorax and a five‐segmented head.

Crustaceans have mandibles and other specialised feeding appendages.

Molting is necessary for crustacean growth and includes the cuticle‐lined gut.

Excretory organs may be specialised as antennal or maxillary glands.

Crustaceans exhibit an incredible diversity and abundance.

Crustaceans range from tiny planktonic or interstitial forms less than a millimetre in length to much larger and often commercially valuable forms such as shrimp, lobsters and crabs.

The crustacean fossil record extends back to the Burgess Shale.

Crustaceans and insects form one large clade, the pancrustaceans.

As traditionally viewed, crustaceans are paraphyletic.
Onychophora (Velvet Worms)
Authors: Wright Jonathan C 
Published: April 2013

Abstract

The phylum Onychophora, also known as ‘peripatus’, ‘velvet worms’ or ‘walking worms’, comprises over 180 described species. Onychophorans are exclusively terrestrial, but are susceptible to desiccation and are restricted to humid microsites. The majority of species inhabit tropical forest litter. Their flexible trunk, retractile limbs and ability to squeeze through small interstices all make them excellently adapted for life in decomposing wood and leaf litter. The head appendages are modified for form sensory antennae, slicing mandibles and slime papillae. The last are a unique trait of onychophorans and eject a rapidly polymerising glue, which is used to entangle their animal prey. Both morphological and molecular phylogenetic studies place the Onychophora at the base of the phylum Arthropoda. Gas exchange via an invaginated tracheal system and water‐conserving uricotely represent show convergent evolution with similar terrestrial adaptations in insects.

Key Concepts:

Onychophorans possess typical arthropod traits: a chitinous cuticle, metameric segmentation with paired segmental limbs and periodic moulting regulated by steroid ecdysones.

Gas exchange in onychophorans is accomplished by spiracles scattered over the body surface and which open into fan‐like clusters of tracheal tubules.

The flexible trunk functions as a hydrostatic skeleton, deformed by antagonising circular and longitudinal muscle layers beneath the integument.

Onychophorans possess little resistance to desiccation and are mostly confined to humid habitats in the tropics and sub‐tropics.

Some species are able to take up water by eversible coxal vesicles at the leg‐bases.

The anterior limbs are specialised as sensory antennae, slicing mandibles and slime papillae that eject a fast‐polymerising glue to entangle prey.

Most onychophorans possess separate sexes (gonochoristic) and fertilisation involves various mechanisms of spermatophore transfer, often during an elaborate courtship.
Tardigrada
Authors: Wright Jonathan C 
Published: April 2013

Abstract

The Tardigrada comprise a phylum of over 1070 described species of minute aquatic animals. The metamerically segmented trunk possesses four pairs of squat, lobopodial limbs with terminating claws; the claw morphology is taxonomically important. Tardigrades are fluid feeders, piercing animal or plant cells with eversible stylets and ingesting fluid with a muscular, pumping pharynx. Two classes are recognised: the Heterotardigrada and Eutardigrada and heterotardigrades include the majority of marine genera. Most tardigrades, however, inhabit interstitial or temporary water bodies in soil, mosses and lichens, surviving periods of drying by cryptobiosis. During this process, animals may sustain a complete loss of ‘free’ liquid water and accompanying cessation of metabolism. In this dehydrated state, tardigrades display suspended senescence and remarkable resistance to environmental extremes. The phylogenetic status of tardigrades has long been contentious, but recent molecular analyses show that tardigrades are basal arthropods and should be reclassified accordingly.

Key Concepts:

Tardigrades, also known as water bears, are minute lobopodial arthropods occurring worldwide from Arctic to tropical latitudes.

All tardigrades are aquatic; they are particularly associated with interstitial water of mosses, lichens and soils.

Two classes are recognised: the Eutardigrada and the Heterotardigrada; the latter includes some marine species.

All tardigrades possess piercing stylets that are used to puncture the cells of plants or, in a few species, animal prey.

In many species of tardigrades, the eggs and adults are capable of surviving extreme dehydration and sub‐freezing temperatures by means of cryptobiosis.

Cryptobiotic organisms frequently accumulate disaccharides or polyols that may stabilise membranes and proteins and/or promote vitrification.

Cryptobiotic tardigrades may be ametabolic and show extreme longevity and high resistance to temperature, radiation and microgravity.

Recent molecular phylogenetic studies unite the Tardigrada and Eutardigrada as a natural group within the collective arthropod taxa (Panarthropoda).
Messel
Authors: Schaal Stephan 
Published: April 2013

Abstract

The Messel site, Germany, is a former maar with lake sediments including a laminated algal rock, the dark‐brown to black Messel oilshale. It became famous with the discovery of its extraordinarily well‐preserved fossils of Middle Eocene age, 47 mya. The spectrum of fossil specimen is unusually extensive and contains plants, insects, fishes, reptiles, amphibian, birds and mammalian fossils. Some insects are preserved with their structural colours and vertebrates can be found with complete and articulated skeletons and even with gut contents. Anaerobe bacteria trace hair, feathers and skin. Messel site enables a view to the evolution and radiation of mammals after the extinction of dinosaurs. The palaeoclimate for the Messel forest was proved by a flora which suggests an equable warm and humid climate with some seasonality. Messel site is unique for the lower Eocene and became United Nations Educational, Scientific and Cultural Organisation (UNESCO) World heritage site in the year 1995.

Key Concepts:

A natural catastrophe established the basis for the Messel maar; numerous water vapour explosions created a volcanic crater, where freshwater lake and oilshale developed.

Messel flora is interpreted as the remains of a warm and humid palaeoclimate with some seasonality.

Preservation of 7 pairs of turtles are the first records worldwide of fossilised copulating vertebrates.

The discovery of the oldest preserved anteater made it possible to reconstruct a connection to South America via Africa before the existence of the maar Messel.

Preservation of complete skeletons, including hair and feathers enable scientists to make statements to the individual strategies of vertebrate locomotion.

Gut contents in vertebrates and coprolites offer a unique opportunity to study feeding and food web.

Some insects like jewel beetles and leaf beetles are preserved with their structural colours, which give them an iridescent metallic hue.