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Pristionchus Pacificus
''Pristionchus pacificus'' is a species of free-living nematodes (roundworms) in the family Diplogastridae. The species has been established as a satellite model organism to ''Caenorhabditis elegans'', with which it shared a common ancestor 200–300 million years ago. The genome of ''P. pacificus'' has been fully sequenced, which in combination with other tools for genetic analysis make this species a tractable model in the laboratory, especially for studies of developmental biology. Mouth dimorphism Like other species of ''Pristionchus'' and many other free-living nematodes, ''P. pacificus'' exhibits a polyphenism in its mouthparts that allows individual nematodes to specialize on different food sources, which has made the species a case study in phenotypic plasticity. The polyphenism has two forms (morphs). The most common type, at least in wild-type lab strains, is the "eurystomatous" morph, which can feed on both bacteria and other nematode species. The "stenostomatous" mo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Nematode
The nematodes ( or ; ; ), roundworms or eelworms constitute the phylum Nematoda. Species in the phylum inhabit a broad range of environments. Most species are free-living, feeding on microorganisms, but many are parasitic. Parasitic worms (helminths) are the cause of soil-transmitted helminthiases. They are classified along with arthropods, tardigrades and other moulting animals in the clade Ecdysozoa. Unlike the flatworms, nematodes have a tubular digestive system, with openings at both ends. Like tardigrades, they have a reduced number of Hox genes, but their sister phylum Nematomorpha has kept the ancestral protostome Hox genotype, which shows that the reduction has occurred within the nematode phylum. Nematode species can be difficult to distinguish from one another. Consequently, estimates of the number of nematode species are uncertain. A 2013 survey of animal biodiversity suggested there are over 25,000. Estimates of the total number of extant species are su ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Stochasticity
Stochastic (; ) is the property of being well-described by a random probability distribution. ''Stochasticity'' and ''randomness'' are technically distinct concepts: the former refers to a modeling approach, while the latter describes phenomena; in everyday conversation, however, these terms are often used interchangeably. In probability theory, the formal concept of a ''stochastic process'' is also referred to as a ''random process''. Stochasticity is used in many different fields, including image processing, signal processing, computer science, information theory, telecommunications, chemistry, ecology, neuroscience, physics, and cryptography. It is also used in finance (e.g., stochastic oscillator), due to seemingly random changes in the different markets within the financial sector and in medicine, linguistics, music, media, colour theory, botany, manufacturing and geomorphology. Etymology The word ''stochastic'' in English was originally used as an adjective with the definit ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Rhabditida
Rhabditida is an order of free-living, parasitic and microbivorous nematodes living in soil. The Cephalobidae, Panagrolaimidae, Steinernematidae, and Strongyloididae seem to be closer to the Tylenchia, regardless of whether these are merged with the Rhabditia or not.Tree of Life Web Project (2002b)Nematoda Version of 2002-JAN-01. Retrieved 2008-NOV-02. Families Rhabditida * Myolaimina **''Incertae sedis'' *** Myolaimoidea **** Myolaimidae * Rhabditina ** Bunonematomorpha *** Bunonematoidea **** Bunonematidae ** Diplogasteromorpha *** Cylindrocorporoidea ****Cylindrocorporidae *** Diplogasteroidea ****Cephalobiidae ****Diplogasteridae ****Diplogasteroididae ** Rhabditomorpha *** Mesorhabditoidea ****Peloderidae *** Rhabditoidea **** Rhabditidae *Spirurina ** Ascaridomorpha *** Ascaridoidea **** Acanthocheilidae ****Anisakidae **** Ascarididae **** Heterocheilidae **** Raphidascarididae *** Cosmocercoidea **** Atractidae **** Kathlaniidae *** Seuratoidea **** Cucullanidae * ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Omnivore
An omnivore () is an animal that regularly consumes significant quantities of both plant and animal matter. Obtaining energy and nutrients from plant and animal matter, omnivores digest carbohydrates, protein, fat, and fiber, and metabolize the nutrients and energy of the sources absorbed. Often, they have the ability to incorporate food sources such as algae, fungi, and bacteria into their diet. Omnivores come from diverse backgrounds that often independently evolved sophisticated consumption capabilities. For instance, dogs evolved from primarily carnivorous organisms (Carnivora) while pigs evolved from primarily herbivorous organisms (Artiodactyla). Despite this, physical characteristics such as tooth morphology may be reliable indicators of diet in mammals, with such morphological adaptation having been observed in bears. The variety of different animals that are classified as omnivores can be placed into further sub-categories depending on their feeding behaviors. Frug ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Scarab Beetle
The family Scarabaeidae, as currently defined, consists of over 35,000 species of beetles worldwide; they are often called scarabs or scarab beetles. The classification of this family has undergone significant change. Several groups formerly treated as subfamilies have been elevated to family rank (e.g., Bolboceratidae, Geotrupidae, Glaresidae, Glaphyridae, Hybosoridae, Ochodaeidae, and Pleocomidae), and some reduced to lower ranks. The subfamilies listed in this article are in accordance with those in Catalog of Life (2023). Description Scarabs are stout-bodied beetles; most are brown or black in colour, but many, generally species that are diurnally active, have bright metallic colours, measuring between . The antennae of most species superficially seem to be knobbed (capitate), but the several segments comprising the head of the antenna are, as a rule, lamellate: they extend laterally into plates called lamellae that they usually keep compressed into a ball. The ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cilia
The cilium (: cilia; ; in Medieval Latin and in anatomy, ''cilium'') is a short hair-like membrane protrusion from many types of eukaryotic cell. (Cilia are absent in bacteria and archaea.) The cilium has the shape of a slender threadlike projection that extends from the surface of the much larger cell body. Eukaryotic flagella found on sperm cells and many protozoans have a similar structure to motile cilia that enables swimming through liquids; they are longer than cilia and have a different undulating motion. There are two major classes of cilia: ''motile'' and ''non-motile'' cilia, each with two subtypes, giving four types in all. A cell will typically have one primary cilium or many motile cilia. The structure of the cilium core, called the axoneme, determines the cilium class. Most motile cilia have a central pair of single microtubules surrounded by nine pairs of double microtubules called a 9+2 axoneme. Most non-motile cilia have a 9+0 axoneme that lacks the central pai ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Self-recognition
In philosophy, self-awareness is the awareness and reflection of one's own personality or individuality, including traits, feelings, and behaviors. It is not to be confused with consciousness in the sense of qualia. While consciousness is being aware of one's body and environment, self-awareness is the recognition of that consciousness. Self-awareness is how an individual experiences and understands their own character, feelings, motives, and desires. Biology Mirror neurons Researchers are investigating which part of the brain allows people to be self-aware and how people are biologically programmed to be self-aware. V.S. Ramachandran speculates that mirror neurons may provide the neurological basis of human self-awareness. In an essay written for Edge.org in 2009, Ramachandran gave the following explanation of his theory: " ese neurons can not only help simulate other people's behavior but can be turned 'inward'—as it were—to create second-order representations or ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Selective Pressure
Evolutionary pressure, selective pressure or selection pressure is exerted by factors that reduce or increase reproductive success in a portion of a population, driving natural selection. It is a quantitative description of the amount of change occurring in processes investigated by evolutionary biology, but the formal concept is often extended to other areas of research. In population genetics, selective pressure is usually expressed as a selection coefficient. Amino acids selective pressure It has been shown that putting an amino acid bio-synthesizing gene like ''HIS4'' gene under amino acid selective pressure in yeast causes enhancement of expression of adjacent genes which is due to the transcriptional co-regulation of two adjacent genes in Eukaryota. Antibiotic resistance Drug resistance in bacteria is an example of an outcome of natural selection. When a drug is used on a species of bacteria, those that cannot resist die and do not produce offspring, while those that ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Larva
A larva (; : larvae ) is a distinct juvenile form many animals undergo before metamorphosis into their next life stage. Animals with indirect development such as insects, some arachnids, amphibians, or cnidarians typically have a larval phase of their life cycle. A larva's appearance is generally very different from the adult form (''e.g.'' caterpillars and butterflies) including different unique structures and organs that do not occur in the adult form. Their diet may also be considerably different. In the case of smaller primitive arachnids, the larval stage differs by having three instead of four pairs of legs. Larvae are frequently adapted to different environments than adults. For example, some larvae such as tadpoles live almost exclusively in aquatic environments but can live outside water as adult frogs. By living in a distinct environment, larvae may be given shelter from predators and reduce competition for resources with the adult population. Animals in the lar ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Generalist And Specialist Species
A generalist species is able to thrive in a wide variety of environmental conditions and can make use of a variety of different resources (for example, a heterotroph with a varied diet). A specialist species can thrive only in a narrow range of environmental conditions or has a limited diet. Most organisms do not all fit neatly into either group, however. Some species are highly specialized (the most extreme case being monophagous, eating one specific type of food), others less so, and some can tolerate many different environments. In other words, there is a continuum from highly specialized to broadly generalist species. Description Omnivores are usually generalists. Herbivores are often specialists, but those that eat a variety of plants may be considered generalists. A well-known example of a specialist animal is the monophagous koala, which subsists almost entirely on eucalyptus leaves. The raccoon is a generalist, because it has a natural range that includes most of Nor ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Diplogastridae
Diplogastridae, formerly Diplogasteridae, are a family of nematodes (roundworms) known from a wide range of habitats, often in commensal or parasitic associations with insects. Description Diplogastrid nematodes are characterized by a distinct "two-lobed" pharynx (hence their name from the Greek διπλόος = "double" and γαστήρ = "stomach"), the second ( posterior) lobe being composed mostly of glandular tissue. Most known species also have at least one tooth, which has presumably allowed them to access many new food sources compared with the related nematodes of Rhabditidae (including ''Caenorhabditis elegans''), most species of which feed on bacteria. Several diplogastrid species also have a polyphenism in their mouthparts, allowing resource specialization within species. The wide array of feeding modes in the Diplogastridae is reflected by the relatively high diversity and complexity of their mouth structures, which show accelerated rates of evolution in comparison ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Wild-type
The wild type (WT) is the phenotype of the typical form of a species as it occurs in nature. Originally, the wild type was conceptualized as a product of the standard "normal" allele at a locus, in contrast to that produced by a non-standard, " mutant" allele. "Mutant" alleles can vary to a great extent, and even become the wild type if a genetic shift occurs within the population. Continued advancements in genetic mapping technologies have created a better understanding of how mutations occur and interact with other genes to alter phenotype. It is now regarded that most or all gene loci exist in a variety of allelic forms, which vary in frequency throughout the geographic range of a species, and that a uniform wild type does not exist. In general, however, the most prevalent allele – i.e., the one with the highest gene frequency – is the one deemed wild type. The concept of wild type is useful in some experimental organisms such as fruit flies ''Drosophila melanogaster'', ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
