DOCSLIB.ORG

The Use of Inflammation by Tumor Cells

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
The Use of Inflammation by Tumor Cells 223 COMMENTARY The Use of Inflammation by Tumor Cells 1 Jose-Ignacio Arias, M.D., Ph.D. 2 Marı´a-Angeles Aller, M.D., Ph.D. 2 Jaime Arias, M.D., Ph.D. 1 Servicio de Cirugı´a General, Hospital Monte Naranco, Oviedo, Asturias, Spain. 2 Ca´tedra de Cirugı´a, Departamento de Cirugı´a I, Facultad de Medicina, Universidad Complutense de Madrid, Madrid, Spain. ancer is malignant, because tumor cells invade neighboring tis- Csues and survive in these ectopic sites. This invasion permits them to enter into the circulation, from which they can reach distant organs and, eventually, form secondary tumors, called metastases.1 The classical metastatic cascade encompasses intravasation by tumor cells, circulation of these cells in lymph and blood vascular systems, arrest in distant organs, extravasation, and growth into met- astatic foci.1,2 However, the tumor cells can adopt a great variety of phenotypes; and, due to this plasticity of the malignant cells; it has been proposed that a more dynamic view is needed for the metastatic cascade.2,3 Invasion and metastases are not unique for cancer, because they also occur during embryonic development, in adult tissue mainte- nance, and in many noncancerous diseases, such as in repair pro- cesses.1,2 In relation to the latter, tumor cells have been described as wounds that do not heal.4 Both tissue repair, a beneficial process, and tumor formation, a harmful process, share some molecular mechanisms that can be ascribed to inflammation.1,2,5 Therefore, in one sense, it is possible that inflammation is shared by both processes: tissue repair and tumor formation. The Possible Trophic Significance of the Inflammatory Response in Tissue Repair To integrate the different alterations that are produced after injury by mechanical energy (posttraumatic inflammation), we consider that a response based on the successive functional predominance of the Supported by grant GE-EJS01-04 from the Princi- nervous, immune, and endocrine systems would be produced. This pado de Asturias, Education and Culture Council. hypothesis implies that the final and prevalent functions of these Address for reprints: Jaime Arias, M.D., Ph.D., systems may represent the consecutive phases of the response to Ca´tedra de Cirugı´a, Facultad de Medicina, Univer- stress, all of which may have trophic significance.6–8 sidad Complutense, Pza. Ramo´n y Cajal s.n., In the nervous phase, ischemia-reperfusion, which causes inter- 28040 Madrid, Spain; Fax: (011) 34 913947115; stitial and cellular edema, is produced. Both types of edema may E-mail: [email protected] represent an ancestral mechanism to feed the cells by diffusion. Received October 31, 2004; revision received Feb- During the immune phase, the tissues are infiltrated by inflammatory ruary 14, 2005; accepted March 3, 2005. cells and bacteria. Hence, extracellular digestion, by enzyme release © 2005 American Cancer Society DOI 10.1002/cncr.21165 Published online 3 June 2005 in Wiley InterScience (www.interscience.wiley.com). 224 CANCER July 15, 2005 / Volume 104 / Number 2 TABLE 1 Inflammatory Response and Tumor Evolution Inflammatory response Tumor cell Nervous phase Immune phase Endocrine phase Benign -Ischemia-reperfusion -Infiltration by inflammatory cells -Extracellular matrix Induces inflammatory response or -Angiogenesis host reaction -Cellular proliferation Desmoplasia Malignant -Hypoxic tumoral cells -Leukocyte tumoral phenotype -Vascularized malignant primitive tumor Adopts an inflammatory -Anaerobic glycolytic metabolism -Anaerobic glycolysis -Oxidative phosphorylation phenotype -Revascularization -Proinflammatory gene expression -Vasculogenic mimicry -Reperfusion injury -Migration and invasion -Angiogenic metastasis -Oxidative stress -Lymph node metastasis -Cachectic syndrome -Nutrition by diffusion -Micrometastasis (preangiogenic or “dormant”) -Nutrition by digestion, (extracellular and intracellular) (fermentation) and intracellular digestion by phagocy- called malignant or cancers that invariably kill their tosis may be associated with a hypothetical trophic host if untreated.1 The invasive capacity of cancers is capacity for the neighboring cells. Finally, in the late reflected in the classic metastatic cascade, which is or endocrine phase, nutrition mediated by the blood staged according to the volume of the primary tumor capillaries is established.7 In these three successive and its depth of invasion (T stage), the number and phases, the inflammatory response progresses from the volume of occupied lymph nodes as well as inva- an anaerobic metabolism (ischemia), through a me- sion through their capsule (N stage), and the presence tabolism characterized by defective oxygen use (reper- of distant metastases (M stage).1 However, if the pre- fusion, oxidative burst, and heat hyperproduction), viously described functional concept of inflammatory and, finally, to an oxidative metabolism (oxidative response is applied to tumor evolution, then this may phosphorylation) with correct use of oxygen to pro- help us to better understand the mechanisms that duce usable energy. This type of metabolism is char- govern their invasive capacity and to obtain a more acterized by a large production of adenosine triphos- dynamic view of the metastatic cascade. phate (ATP), which is used to drive specialized The tumor benign cells seem to be able to induce multiple cellular processes.7,9,10 an inflammatory response in the host. Therefore, it is Because the nervous, immune, and endocrine possible that the host may participate in establish- phases of the inflammatory response progress from ment of the tumor by a process called desmoplasia, ischemia to the development of an oxidative metabo- consisting of fibroblastic cells and extracellular matrix lism, it also is tempting to speculate on whether the as inflammation and immune response, represented body reproduces the successive stages by which life by lymphocytes, macrophages, and dendritic cells, passes from its origin without oxygen until it develops and as angiogenesis, evidenced by newly formed an effective, although costly, system for the use of blood and lymph vessels.1 Essentially, all of the ele- oxygen every time we suffer posttraumatic acute in- ments that constitute the inflammatory response par- flammation.9,10 Likewise, the successive expression of ticipate in this “host reaction” that, thus, may have a these three functional systems during embryonic de- trophic purpose for the tumor cells7,9 (Table 1). velopment and also during the evolutionary develop- The nutritional importance of this host cell reac- ment of our species may explain why the inflamma- tion for tumor cells, manifested by leukocytes, blood tory response is a ubiquitous mechanism that is vessels, and stroma, would explain why these host common to multiple diseases, because it is an integra- elements, although more abundant in some types of tor of the ontogeny and phylogeny.7 cancer than in others, are omnipresent.1 However, when tumor cells reach higher grades of malignancy, Inflammatory Response and Tumors their invasive capacity seems to be more of a reflection Tumors can be noninvasive or benign, because they of the new capacity to express the inflammatory re- are cured easily by simple removal, and invasive—also sponse than to induce it in the host. In this hypothet- Inflammation and Cancer/Arias et al. 225 ical circumstance, the successive phases that have turn, this system can be regulated by hypoxia and/or been described in the posttraumatic inflammatory re- reoxygenation.11 More specifically, the expression of sponse would be expressed by tumor cells and would inducible genes leading to the synthesis of cytokines, express their evolution with invasion and metastases chemokines, adhesion molecules, and autacoids relies (Table 1). on transcription factors; and, among the primary tran- Thus, the first evolutive or nervous phase would scription factors, NF-␬B plays a central role in the be characterized by the ischemia-reperfusion phe- regulation of inflammatory mediators.17 nomenon. In this sense, the tumor cell seems to adopt Activation of the general stress-responsive tran- an ischemic phenotype (hypoxic),11,12 which, when it scription factors, such as NF-␬B, in the tumor cells11 comes into contact with oxygen, undergoes a process may imply their transition to a hypothetical phase of revascularization. The transcriptional response to called an immune phase, because this may be associ- hypoxia relies on multiprotein complexes to regulate ated with proinflammatory gene expression. Hence, several transcription factors, the most well studied of tumor cells may usurp key mechanisms by which in- which is hypoxia inducible factor-1 (HIF-1), which flammation interfaces with cancer to further their col- that enhances the expression of hypoxia-responsive onization of the host.18 genes and, thus, allows improved cell survival in con- The association between inflammation and cancer ditions of limited oxygen availability.11,12 can be established by studying the influence of inflam- Hypoxic tumor cells change to an anaerobic gly- matory cells in tumoral progression. Currently, the tu- colytic metabolism as the main source of ATP, become mor microenvironment, which is orchestrated largely by resistant to apoptosis (programmed cell death), inflammatory cells, is considered an important partici- present inhibition of differentiation, and become pant in the neoplastic process, because it may foster the more likely to migrate to less hypoxic areas.12 More- spread of tumors.18 In addition, solid tumors are infil-
Load more

Recommended publications
  • A Non-Bilaterian Perspective on the Development and Evolution of Animal Digestive Systems
    Cell and Tissue Research (2019) 377:321–339 https://doi.org/10.1007/s00441-019-03075-x REVIEW A non-bilaterian perspective on the development and evolution of animal digestive systems Patrick R. H. Steinmetz 1 Received: 22 March 2019 /Accepted: 8 July 2019 /Published online: 7 August 2019 # The Author(s) 2019 Abstract Digestive systems and extracellular digestion are key animal features, but their emergence during early animal evolution is currently poorly understood. As the last common ancestor of non-bilaterian animal groups (sponges, ctenophores, placozoans and cnidarians) dates back to the beginning of animal life, their study and comparison provides important insights into the early evolution of digestive systems and functions. Here, I have compiled an overview of the development and cell biology of digestive tissues in non-bilaterian animals. I will highlight the fundamental differences between extracellular and intracellular digestive processes, and how these are distributed among animals. Cnidarians (e.g. sea anemones, corals, jellyfish), the phylogenetic outgroup of bilaterians (e.g. vertebrates, flies, annelids), occupy a key position to reconstruct the evolution of bilaterian gut evolution. A major focus will therefore lie on the development and cell biology of digestive tissues in cnidarians, especially sea anemones, and how they compare to bilaterian gut tissues. In that context, I will also review how a recent study on the gastrula fate map of the sea anemone Nematostella vectensis challenges our long-standing conceptions on the evolution of cnidarian and bilaterian germ layers and guts. Keywords Cnidaria . Porifera . Placozoa . Ctenophora . Gastrovascular system . Gut evolution . Extracellular digestion . Intracellular digestion . Germ layer evolution Introduction ester bonds.
    [Show full text]
  • Prey Capture and Digestion in the Carnivorous Sponge Asbestopluma Hypogea (Porifera: Demospongiae)
    Zoomorphology (2004) 123:179–190 DOI 10.1007/s00435-004-0100-0 ORIGINAL ARTICLE Jean Vacelet · Eric Duport Prey capture and digestion in the carnivorous sponge Asbestopluma hypogea (Porifera: Demospongiae) Received: 2 May 2003 / Accepted: 17 March 2004 / Published online: 27 April 2004 Springer-Verlag 2004 Abstract Asbestopluma hypogea (Porifera) is a carnivo- Electronic Supplementary Material Supplementary ma- rous species that belongs to the deep-sea taxon Cla- terial is available in the online version of this article at dorhizidae but lives in littoral caves and can be raised http://dx.doi.org/10.1007/s00435-004-0100-0 easily in an aquarium. It passively captures its prey by means of filaments covered with hook-like spicules. Various invertebrate species provided with setae or thin appendages are able to be captured, although minute crus- Introduction taceans up to 8 mm long are the most suitable prey. Multicellular animals almost universally feed by means of Transmission electron microscopy observations have been a digestive tract or a digestive cavity. Apart from some made during the digestion process. The prey is engulfed parasites directly living at the expense of their host, the in a few hours by the sponge cells, which migrate from only exceptions are the Pogonophores (deep-sea animals the whole body towards the prey and concentrate around relying on symbiotic chemoautotrophy and whose larvae it. A primary extracellular digestion possibly involving have a temporary digestive tract) and two groups of mi- the activity of sponge cells, autolysis of the prey and crophagous organisms relying on intracellular digestion, bacterial action results in the breaking down of the prey the minor Placozoa and, most importantly, sponges (Po- body.
    [Show full text]
  • Arboreal Arthropod Predation on Early Instar Douglas-Fir Tussock Moth Redacted for Privacy
    AN ABSTRACT OF THE THESIS OF Becky L. Fichter for the degree of Doctor of Philosophy in Entomologypresented onApril 23, 1984. Title: Arboreal Arthropod Predation on Early Instar Douglas-fir Tussock Moth Redacted for privacy Abstract approved: William P. StOphen Loss of early instar Douglas-fir tussock moth( Orgyia pseudotsugata McDunnough) (DFTM) has been found to constitute 66-92% of intra-generation mortality and to be a key factor in inter-generation population change. This death has been attributed to dispersal and to arthropod predation, two factors previously judged more important to an endemic than an outbreak population. Polyphagous arthropod predators are abundant in the forest canopy but their predaceous habits are difficult to document or quantify. The purpose of the study was to develop and test a serological assay, ELISA or enzyme-linked immunosorbent assay, for use as an indirect test of predation. Development of this assay involved production of an antiserum reactive with DFTM but not reactive with material from any coexisting lepidopteran larvae. Two-dimensional immunoelectrophoresis was used to select a minimally cross-reactive fraction of DFTM hemolymph as the antigen source so that a positive response from a field-collected predator would correlate unambiguously with predation on DFTM. Feeding trials using Podisus maculiventris Say (Hemiptera, Pentatomidae) and representative arboreal spiders established the rate of degredation of DFTM antigens ingested by these predators. An arbitrary threshold for deciding which specimens would be considered positive was established as the 95% confidence interval above the mean of controls. Half of the Podisus retained 0 reactivity for 3 days at a constant 24 C.
    [Show full text]
  • Phylum Porifera
    790 Chapter 28 | Invertebrates updated as new information is collected about the organisms of each phylum. 28.1 | Phylum Porifera By the end of this section, you will be able to do the following: • Describe the organizational features of the simplest multicellular organisms • Explain the various body forms and bodily functions of sponges As we have seen, the vast majority of invertebrate animals do not possess a defined bony vertebral endoskeleton, or a bony cranium. However, one of the most ancestral groups of deuterostome invertebrates, the Echinodermata, do produce tiny skeletal “bones” called ossicles that make up a true endoskeleton, or internal skeleton, covered by an epidermis. We will start our investigation with the simplest of all the invertebrates—animals sometimes classified within the clade Parazoa (“beside the animals”). This clade currently includes only the phylum Placozoa (containing a single species, Trichoplax adhaerens), and the phylum Porifera, containing the more familiar sponges (Figure 28.2). The split between the Parazoa and the Eumetazoa (all animal clades above Parazoa) likely took place over a billion years ago. We should reiterate here that the Porifera do not possess “true” tissues that are embryologically homologous to those of all other derived animal groups such as the insects and mammals. This is because they do not create a true gastrula during embryogenesis, and as a result do not produce a true endoderm or ectoderm. But even though they are not considered to have true tissues, they do have specialized cells that perform specific functions like tissues (for example, the external “pinacoderm” of a sponge acts like our epidermis).
    [Show full text]
  • Ecological Physiology of Diet and Digestive Systems
    PH73CH04-Karasov ARI 3 January 2011 9:50 Ecological Physiology of Diet and Digestive Systems William H. Karasov,1,∗ Carlos Martınez´ del Rio,2 and Enrique Caviedes-Vidal3 1Department of Forest and Wildlife Ecology, University of Wisconsin, Madison, Wisconsin 53706; email: [email protected] 2Department of Zoology and Physiology, University of Wyoming, Laramie, Wyoming 82070; email: [email protected] 3Departamento de Bioquımica´ y Ciencias Biologicas,´ Universidad Nacional de San Luis and Instituto Multidisciplinario de Investigaciones Biologicas´ de San Luis, Consejo Nacional de Investigaciones Cientıficas´ y Tecnicas,´ 5700 San Luis, Argentina; email: [email protected] Annu. Rev. Physiol. 2011. 73:69–93 Keywords The Annual Review of Physiology is online at adaptation, hydrolases, transporters, microbiome physiol.annualreviews.org This article’s doi: Abstract 10.1146/annurev-physiol-012110-142152 The morphological and functional design of gastrointestinal tracts of Copyright c 2011 by Annual Reviews. by University of Wyoming on 02/14/11. For personal use only. many vertebrates and invertebrates can be explained largely by the in- All rights reserved teraction between diet chemical constituents and principles of economic 0066-4278/11/0315-0069$20.00 design, both of which are embodied in chemical reactor models of gut Annu. Rev. Physiol. 2011.73:69-93. Downloaded from www.annualreviews.org ∗Corresponding author. function. Natural selection seems to have led to the expression of diges- tive features that approximately match digestive capacities with dietary loads while exhibiting relatively modest excess. Mechanisms explain- ing differences in hydrolase activity between populations and species include gene copy number variations and single-nucleotide polymor- phisms.
    [Show full text]
  • Club Fungi) • Imperfect Fungi Are Those Not Yet Classified Fungal Classification Zygomycetes Sac Fungi Club Fungi
    Chapter 24: Fungi Fig. 24-1a, p.390 Lichen • Combination of fungus and photosynthetic organism(s) • Organisms are symbionts • Relationship is a mutualism Review: Mycorrhiza • “Fungus-root” • Mutualism between a fungus and a tree root • Fungus gets sugars from plant • Plant gets minerals from fungus • Many plants do not grow well without mycorrhizae Fungi as Decomposers • Break down organic compounds in their surroundings • Carry out extracellular digestion and absorption • Plants benefit because some carbon and nutrients are released A Variety of Roles • Pathogens • Spoilers of food supplies • Used to manufacture –Antibiotics –Cheeses Fungi Are Heterotrophs • Cannot carry out photosynthesis • Must acquire organic molecules from the environment • Most are saprobes – Get nutrients from nonliving organic matter • Some are parasites – Extract nutrients from a living host The Mycelium • Most fungi produce a multicellular feeding structure called a mycelium • It consists of branching tubular cells called hyphae • Cell walls contain chitin The Mycelium one cell (part of one hypha of the mycelium) p.392 Extracellular Digestion • Mycelium grows into food source • Tips of hyphae secrete digestive enzymes • Enzymes break down organic material into simple forms that can be absorbed by hyphae Fungal Life Cycle • No motile stage • Asexual and sexual spores produced • Spores germinate after dispersal • In multicelled species, spores give rise to a new mycelium Fungal Classification • Fungi known from 900 mya • 56,000 known species • Three major lineages: – Zygomycota – Ascomycota (sac fungi) – Basidiomycota (club fungi) • Imperfect fungi are those not yet classified Fungal Classification zygomycetes sac fungi club fungi chytrids microsporidians FUNGI amoeboid ancestors Fig. 24-2, p.392 Fungal Classification Fig.
    [Show full text]
  • Nutrition and Digestion MODULE - 2 Forms and Function of Plants and Animals
    Nutrition and Digestion MODULE - 2 Forms and Function of Plants and Animals 13 Notes NUTRITION AND DIGESTION Plants manufacture their own food by photosynthesis, but all animals including humans have to take in ready made food. Most part of such food consists of complex organic molecules (carbohydrates, proteins and fats) which have to be broken down into simpler forms before they can be absorbed into the body. Such breaking down of the food and subsequent absorption of food constituents occur inside the digestive tract (alimentary canal). The digestive tract together with the associated glands constitute the digestive system. OBJECTIVES After studying this lesson, you will be able to : l define the term nutrition and give its types; l draw a labelled diagram of the alimentary canal of cockroach and humans; l describe the steps involved in the nutrition of humans viz., ingestion, digestion, absorption, assimilation and egestion; l differentiate between intracellular and intercellular digestion; l tabulate the organs of digestion, the enzymes they secrete, the substances acted upon by enzymes and the end products formed. l explain the process of food absorption in various regions of digestive tract; l explain briefly the role of hormones in digestion. 13.1 NUTRITION AND DIGESTION Our food contains a number of food constituents to meet the requirements of our body. These food constituents must be digested to be utilized by our body. The process by which organisms obtain and utilize food for their growth, development and maintenance is called nutrition and the chemicals present in the food are called nutrients. On the other hand, digestion is the breaking down of complex constituents of food by enzymes into simpler soluble forms that can be absorbed and utilised by the cells of the body.
    [Show full text]
  • Feeding & Digestion
    Feeding & Digestion Why eat? • Macronutrients Feeding & Digestion – Energy for all our metabolic processes – Monomers to build our polymers 1. Carbohydrates 2. Lipids 3. Protein • Micronutrients – Tiny amounts of vital elements & compounds our body cannot adequately synthesize 4. Vitamins 5. Minerals • Hydration 6. Water Niche: role played in a FEEDING community (grazer, predator, • “Eat”: Gr. -phagy; Lt. -vore scavenger, etc.) • Your food may not Some organisms have specialized niches so as to: • increase feeding efficiency wish to be eaten! • reduce competition • DIET & Optimal foraging model: Need to maximize benefits (energy/nutrients) while minimizing MORPHOLOGY costs (energy expended/risks) • FOOD CAPTURE • MECHANICAL PROCESSING Never give up! Optimal Foraging Model Optimal Foraging Model • Morphology reflects foraging strategies • Generalist is less limited by rarity of resources • Specialist is more efficient at exploiting a specific resource Generalist OMNIVORE opossum CARNIVORE HERBIVORE wolf elephant Optimal foraging strategies: Need to maximize benefits (energy/nutrients) INSECTIVORE PISCIVORE while minimizing costs (energy shrew osprey expended / risks) MYRMECOPHAGORE • Tapirs have 40x more meat, but are anteater much harder to find and catch. Specialist So jaguars prefer armadillos. Heyer 1 Feeding & Digestion Bird Beaks Anteater Adaptations • Generalist & specialist bills • Thick fur • Small eyes • Long claws in front • Long snout • Long barbed tongue • No teeth FOOD CAPTURE SPECIALIZATIONS Fluid Feeding – Fluid Feeding • Sucking with tube – Suspension & Deposit Feeding – mosquitoes & butterflies • Lapping with brushy tongue – Grazers & Browsers – hummingbirds, fruit bats – Predation: Ambush & Attraction – bees – Venoms – Tool Use & Team Efforts Hummingbird tongue Suspension Feeding (Filter Feeding) • Filter food (plankton, small animals, organic particles) suspended in water. • http://www.youtube.com/watch?v=1wpQ8HQEkvE • Filters are hard, soft or even sticky.
    [Show full text]
  • High Throughput Techniques to Reveal the Molecular Physiology and Evolution of Digestion in Spiders Felipe J
    Fuzita et al. BMC Genomics (2016) 17:716 DOI 10.1186/s12864-016-3048-9 RESEARCH ARTICLE Open Access High throughput techniques to reveal the molecular physiology and evolution of digestion in spiders Felipe J. Fuzita1,2, Martijn W. H. Pinkse3, José S. L. Patane4, Peter D. E. M. Verhaert3,5 and Adriana R. Lopes1* Abstract Background: Spiders are known for their predatory efficiency and for their high capacity of digesting relatively large prey. They do this by combining both extracorporeal and intracellular digestion. Whereas many high throughput (“-omics”) techniques focus on biomolecules in spider venom, so far this approach has not yet been applied to investigate the protein composition of spider midgut diverticula (MD) and digestive fluid (DF). Results: We here report on our investigations of both MD and DF of the spider Nephilingis (Nephilengys) cruentata through the use of next generation sequencing and shotgun proteomics. This shows that the DF is composed of a variety of hydrolases including peptidases, carbohydrases, lipases and nuclease, as well as of toxins and regulatory proteins. We detect 25 astacins in the DF. Phylogenetic analysis of the corresponding transcript(s) in Arachnida suggests that astacins have acquired an unprecedented role for extracorporeal digestion in Araneae, with different orthologs used by each family. The results of a comparative study of spiders in distinct physiological conditions allow us to propose some digestion mechanisms in this interesting animal taxon. Conclusion: All the high throughput data allowed the demonstration that DF is a secretion originating from the MD. We identified enzymes involved in the extracellular and intracellular phases of digestion.
    [Show full text]
  • Six Major Steps in Animal Evolution: Are We Derived Sponge Larvae?
    EVOLUTION & DEVELOPMENT 10:2, 241–257 (2008) Six major steps in animal evolution: are we derived sponge larvae? Claus Nielsen Zoological Museum (The Natural History Museum of Denmark, University of Copenhagen), Universitetsparken 15, DK-2100 Copenhagen, Denmark Correspondence (email: [email protected]) SUMMARY A review of the old and new literature on animal became sexually mature, and the adult sponge-stage was morphology/embryology and molecular studies has led me to abandoned in an extreme progenesis. This eumetazoan the following scenario for the early evolution of the metazoans. ancestor, ‘‘gastraea,’’ corresponds to Haeckel’s gastraea. The metazoan ancestor, ‘‘choanoblastaea,’’ was a pelagic Trichoplax represents this stage, but with the blastopore spread sphere consisting of choanocytes. The evolution of multicellularity out so that the endoderm has become the underside of the enabled division of labor between cells, and an ‘‘advanced creeping animal. Another lineage developed a nervous system; choanoblastaea’’ consisted of choanocytes and nonfeeding cells. this ‘‘neurogastraea’’ is the ancestor of the Neuralia. Cnidarians Polarity became established, and an adult, sessile stage have retained this organization, whereas the Triploblastica developed. Choanocytes of the upper side became arranged in (Ctenophora1Bilateria), have developed the mesoderm. The a groove with the cilia pumping water along the groove. Cells bilaterians developed bilaterality in a primitive form in the overarched the groove so that a choanocyte chamber was Acoelomorpha and in an advanced form with tubular gut and formed, establishing the body plan of an adult sponge; the pelagic long Hox cluster in the Eubilateria (Protostomia1Deuterostomia). larval stage was retained but became lecithotrophic. The It is indicated that the major evolutionary steps are the result of sponges radiated into monophyletic Silicea, Calcarea, and suites of existing genes becoming co-opted into new networks Homoscleromorpha.
    [Show full text]
  • UNIT 1 NUTRITION, FEEDING, DIGESTION Structure Introduction Objectives Nutrition Proteins Carbohydrates Lipids Vitamins
    UNIT 1 NUTRITION, FEEDING, DIGESTION Structure Introduction Objectives Nutrition Proteins Carbohydrates Lipids Vitamins. Minerals and Trace Elements Water Feeding Mechanisms Feeding on Small Particles Fteding on Food Masses Feeding on Liquids Digestion lntrllccllular Digestion Digestive Tract Dibestive Enzymes Maintenance of Gut Lining Coordination of Digestion Absorption Energy Metab-olism Summary Terminal Questions Answers 1.1 INTRODUCTION All organisms require a fairly steady supply of nutrient materials from the environment to obtain energy in order to stay alive. You would recall from FST-1, Unit 14 that animals are heterotrophs because they depend on already synfhesised organic compounds from plants and other animals to obtain their food. Unlike autotrophs (plants and chemosynthetic bacteria) animals have only limited synthesising abilitiks. In LSE-01, you have read that cellular metabolism provides energy for various processes in organisms, like locomotion., excretion, osmoregulation, synthesis of new materials for growth and maintenance and reproduction. To provide energy for these processes raw material or nutrients are required which are supplied by food. In addition animals require amino acids, vitamins and minerals which they cannot synthesise. The study of nutrition involves both the need for food to provide energy and the need for specific food components. The process by which animajs acquire and ingest their food is referred to as feeding. Diverse types of feeding mechanisms have been evolved by different groups of animals. Virtually all foofwhether of plant or of animal origin has to be broken down to simple compounds by the process of digestion. Digestion and absorption of food constitute the essential link between nutrition and metabolism.
    [Show full text]
  • BIOL 2015 – Evolution and Diversity Lab 7: Porifera, Cnidaria and Ctenophora
    BIOL 2015 – Evolution and Diversity Lab 7: Porifera, Cnidaria and Ctenophora IntroduCtion In terms of known living organisms, animals are the most specious group of organisms on Earth. They come in a wide variety of shapes, sizes, and structure. In fact, there are over 35 phyla of animals and it is a continuing challenge for biologists to understand both the phylogenetic relationships among animals and the evolutionary processes that produced the great diversity we see today (a modern phylogenetic tree is shown in Figure 1). There are a few underlying themes in animal evolution which you should keep in mind during the next series of labs. Two related themes are: 1. Evolution of Motility. The ability to find food and escape predation is an important part of life for most animals. Motility was a key innovation and is found in the majority of animals. 2. AdvanCed Heterotrophy. Sophisticated means of prey capture allow animals to consume larger quantities of different kinds of food. Much of the diversity evident in animals comes from different ways animals have evolved to obtain food. Animals are multicellular heterotrophs. That is, they are made of many cells and they don’t make their own food. The simplest animals, the sponges, do not have a gut and cannot move in search of food. They have evolved a pump-like mechanism to move nutrients suspended in water past the individual cells that make up their body. As nutrients pass these cells they are taken up via endocytosis and digested within the each cell. Most animals move about in search of food and have a gut within which digestion can occur.
    [Show full text]