emerging cell surface display systems insect cell and mammalian cell display
Insect cell baculovirus display is a well-established technology, yet unlike bacterial or yeast surface display, this system has not been extensively used for protein engineering applications Makela and Oker-Blom 2006 Makela and Oker-Blom 2008 . Despite the relatively few examples of protein engineering with insect cell baculo-virus systems, which require greater expertise in handling compared to microbial-based systems, recent studies have shown much potential. This format involves either the...
The Animal Tree
There are about 35 living animal phyla. To understand the origin and evolution of any feature found in one or more of these groups, it is necessary to have a picture of the phylogenetic relationships among animals. Ideally, the fossil record would present a complete, ordered, unambiguous picture of the branching pattern of the animal tree. Unfortunately, it does not. As the divergence of most bilaterian phyla appears to have predated the emergence of recognizable members of modern phyla in the...
embryological data and its phylogenetic implications
It is now more than a century since embryological studies the Reichert-Gaupp theory, refuted by Otto 1984 demonstrated the homology of the mammalian malleus and incus with the articular and quadrate bones which formed the ancestral jaw joint of gnathostomes. This tremendous transition can be traced in fossils by comparing basal synapsids through therapsids to early mammals. A fetal mammal shows that the angular tympanic , articular malleus , and quadrate incus develop in the same positions they...
231 Functional morphology
The first question that people ask about any fossil vertebrate is 'what did it do ' Just how did the heavily armoured Devonian fishes manage to swim Why did some mammal-like reptiles have massively thick skull roofs What did Stegosaurus use its back plates for Why did sabre-toothed cats have such massive fangs These are all questions of functional morphology, the interpretation of function from morphology, the shape and form of an animal. The main assumption behind this approach is that...
Basic Morphology
Maxillary incisors range within and among Malagasy lemurs from entirely absent Lepilemur or reduced lemurids, Avahi to relatively prominent cheirogaleids, indriids see Table 1 Martin, 1972 Tattersall, 1982 . Maxillary canine size varies considerably among lemurs, with some taxa exhibiting very large i.e., high canines, relative to first molar size see Table 3 in Godfrey et al., this volume . Daubentonia has no permanent canines Swindler, 2002 Tattersall, 1982 . In Hapalemur, the maxillary...
Ichthyosaurs
Ichthyosaurs first appeared in the Lower Triassic alongside the placodonts and nothosaurs. They were the most highly specialised of all aquatic reptiles, and evolved to become top marine predators, yet maintained essentially the same body shape throughout most of the Mesozoic Era - about 150 million years. Like nothosaurs, thalattosaurs, crocodilians and other amphibious reptiles, plesiosaurs would almost certainly have been ectothermal as are modern crocodiles. These usually sun themselves...
How dendrochronology works
Tree rings are not quite the only system that promises total accuracy to the nearest year. Varves are layers of sediment laid down in glacial lakes. Like tree rings, they vary seasonally and from year to year, so theoretically the same principle can be used, with the same degree of accuracy. Coral reefs, too, have annual growth rings, just like trees. Fascinatingly, these have been used to detect the dates of ancient earthquakes. Tree rings too, by the way, tell us the dates of earthquakes....
Drifting Continents And Globetrotting Dinosaurs
dinosaurs got around. Their fossilized remains occur on every continent and from pole to pole, encompassing a tremendous variety of ancient environments forests, savannahs, deserts, seashores, river floodplains, and mountain valleys, among others. How did these prehistoric landlubbers disperse across oceanic barriers to populate the globe Did they make marathon swims particularly challenging for tyrannosaurs, given their tiny arms , or climb aboard vast mats of floating vegetation No, we now...
Image Not Available 1
Figure 2.3 The medusoid phase of a living aequorian hydroid. Diameter approximately 1 cm. compaction, would have been greater. In chapter 5 we see how recognition of the convex-side-down aspect of Ediacaran medusoids was the precursor to Garden of Ediacara theory, the concept that these medu-soids were actually bowl-shaped solar collectors. Many Ediacaran medusoids are three-dimensional fossils filled with fine sediment. The Mexican specimen figure 2.1 is one of these, as is the Irish find. How...
Cladistics
The points at which groups of organisms have separated are difficult to determine. Cladistic analysis attempts to identify these branching points and to establish evolutionary relationships between a diverse group of organisms. Closely related groups have shared characters termed shared derived characters. Features shared by the entire group of organisms are termed primitive. Characters may be called primitive or derived depending on the level of classification. For example, feathers would be...
1 What Are Relicts
Dictionaries define a relict as something that has survived, usually as a trace, from the past. In biology, relicts are distinctive populations or species that typically are small in size or severely restricted in geographic range. Biologists distinguish between taxonomic and biogeographic relicts. Taxonomic relicts are a few or sole survivors of a once diverse taxonomic assemblage, whereas biogeographic relicts are descendants of once widespread taxa or populations that now have a narrow...
Continental Drift
In order to interpret the distribution and consequent diversification of the Mesozoic reptiles, one has to realise that continents are by no means static. During Cambrian times, some 500 mya million years ago , they were distributed along the equatorial belt of the world. They included Laurentia, Siberia, Baltica, Avalonia and the enormous Gondwanaland, the only one to extend into temperate latitudes. During the course of Silurian and Devonian periods, approximately 400 mya Table 1 ,...
Insects Were The First Domesticators
Roses tell the same story as dogs, but with one difference, which is relevant to our softening-up strategy. The flower of the rose, even before human eyes and noses embarked on their work of genetic chiselling, owed its very existence to millions of years of very similar sculpting by insect eyes and noses well, antennae, which is what insects smell with . And the same is true of all the flowers that beautify our gardens. The sunflower, Helianthus annuus, is a North American plant whose wild...
Artificial Gravity Assist
Interplanetary space probes often take advantage of the gravity pull of planets and large moons to alter course and gain speed. For these so-called gravity assist maneuvers, a spacecraft flies by a planet and uses its gravitational field and the planet's orbital velocity around the Sun to pick up speed and change direction. It can be somewhat compared to a Ping-Pong ball hitting a revolving fan the ball will bounce back at a much higher speed and in a different direction from which it was hit...
The case of the stolen tooth whorl
Helicoprion bessonowi is one of the world's great enigmas. When it was found in the Russian Ural Mountains in 1899 it aroused great curiosity in the world of natural history. It was a single, curled row of shark's teeth, some 125 in all, which looked more like an ammonite than a shark's jaw. Each tooth was serrated and overlapped the front of its predecessor. Helicoprion whorls indicate that the whole shark must have been a monster, perhaps 8-12 metres in length. We can only hypothesise that...
Introduction to Paleobotany
The Objectives of Paleobotany 2 Form and Function in Fossil Plants 4 Biostratigraphy and Correlation 4 Paleoecology Plants in Their Environment 5 Determining Paleoclimate from Fossil Plants 6 Summary 7 Preservation How Plant Fossils are Formed and Depositional Environments of Fossil Plants 8 Biofilms and Plant Fossil Preservation 16 Geochronology and Biostratigraphy 36 Systematics and Classification 40 Nomenclature of Fossil Plants 41
31 External Features of the Ammonitella
Ornament for all taxa consists of transverse lirae that cover the entire ammonitella except for a bald spot at the apex Klofak et al., 1999 . Wrinkle-like creases stretch between the lirae and are best defined on the initial chamber. These wrinklelike creases are most strongly expressed in the Mimagoniatitidae Figs. 2.1b, 2.2e , less strongly expressed in the Anarcestidae Fig. 2.3b , and least strongly expressed in the Agoniatitidae Fig. 2.1f . The lirae are a relief feature and are not...
gonic syngonic
amphigony n. Gr. amphi, on both sides gonos, seed biparental or bisexual reproduction. amphigonus a. amphihaploid n. Gr. amphi, on both sides haploos, simple eidos, form Said of haploid types produced from amphi-diploids. amphikaryon n. Gr. amphi, on both sides karyon, nut The nucleus of the zygote produced in the course of fertilization containing two haploid genomes. see diplokaryon. amphimict n. Gr. amphi, on both sides miktos, mixed Reproduction by amphimixis. amphimixis n. Gr. amphi, on...
Medusoids
The most common Ediacaran body fossils were the first type discovered at the classic site in the Ediacara Hills, South Australia. Circular or discoid Ediacarans are conventionally called medusoids, in an intentional comparison to the free-swimming medusa phase of the jellyfish life cycle. This is perhaps unfortunate because it is by no means certain that Ediacaran medusoids were related to the jellyfish medusa. However, the name has stuck.8 The term medusa refers to the tentacles of living...
43 Barberton Sulfur Isotopes
A similar sulfur isotope story to that in the Pilbara emerges in the Barberton area from the work of Ohmoto et al. 1993 . These authors sampled a shale and three black cherts from the uppermost Onverwacht Group 3,300 Ma Mendon Formation in the Barberton and used high resolution laser ablation mass spectroscopy to analyse individual pyrite grains. The range of 534S values up to 12 o variation from these pyrites was argued to be greater than that expected if they had formed from purely magmatic...
6 Floral Relationships of Bees
Wind and bees are the world's most important pollinating agents. Bees are either beneficial or actually essential for the pollination, and therefore for the sexual reproduction, of much of the natural vegetation of the world, as well as for many agricultural crops see Sec. 3 . The pollinators are primarily female bees, which collect pollen as the principal protein source in their own food and especially to feed their larvae. Flowers produce not only nectar and sometimes oil but also excess...
9 Conclusion
There are two great facts about life that shed a new light on the mechanisms of evolution. The first is that genes and proteins are produced by copying and coding, by transcription and translation, i.e. by two fundamentally different mechanisms. The second is that natural selection is the long-term result of copying, i.e. of only one of those two basic mechanisms. This implies that coding is a distinct mechanism of molecular change and, in the long run, a distinct mechanism of evolutionary...
A Class 0 Protostars and Other YSO Stages
1. InfraredYSOClasses. of YSOs can be distinguished based on the slopes of their SEDs between 2.2 m and 10-25 m, aIR d log AFA d log A , which are interpreted in terms of an evolutionary sequence Lada and Wilking 1984 Lada 1987 . Going backward in time, Class III aIR lt -1.5 and Class II -1.5 lt aIR lt 0 sources correspond to pre-main-sequence PMS stars weak and classical T Tauri stars, respectively , surrounded by a circumstel-lar disk optically thin in Class III and optically thick in Class...
Archaeopteryx
When Archaeopteryx remains were first unearthed, the dinosaur was thought to be a Compsognathus. However, palaeontologists soon realized that this is one of the most important dinosaur discoveries ever made. Family Coelundea Period Late Jurassic Where found Germany Heiaht 0.3 metre 1 foot
31 Opisthokonts
There are two main opisthokont groups the animals and the fungi. The Proterozoic fossil record of animals is worthy of an extensive review in its own right I will not discuss it here except to note that the earliest well accepted evidence for animals are 580 Ma phosphatized embryos from the Doushantuo Formation, China Xiao et al., 1998b Xiao and Knoll, 2000 Condon et al., 2005 . See papers by Jensen et al. and Bottjer and Clapham, both in this volume, for further information on Proterozoic...
Whats In A Name
The rather timid-looking creature was biscuit coloured, and I immediately thought it was a Labrador dog. But there was something strange about the head and face which puzzled me. It was higher and wider across the forehead than a Labrador, and the face was longer and thinner. Perhaps it was just a 'bitzer', with some Labrador in it. I was quite alone as my companions had gone off to look for a track leading towards Macquarie Harbour. Not even a bird call, a creaking branch . . . disturbed the...
2111 Introduction
The phenomenon of isostasy concerns the response of the outer shell of the Earth to the imposition and removal of large loads. This layer, although relatively strong, is unable to support the large stresses generated by, for example, the positive weight of a mountain range or the relative lack of weight of an ocean basin. For such features to exist on the Earth's surface, some form of compensating mechanism is required to avoid the large stresses that would otherwise be generated. Isostasy was...
Origin and earliest fossil records of hexapods
The sparse fossil record of mid-Palaeozoic hexapods, the pattern of colonization of land by Palaeozoic plant and arthropod groups, and temporal constraints on hexapod origins imposed by hypotheses of arthropod phylogeny on hexapod origins all suggest that the earliest hexapods probably appeared during the Late Silurian. Although often used as a synonym for 'Insecta', the term 'Hexa-poda' designates the more inclusive clade that consists of the Collembola springtails and Protura proturans ,...
iiPreventing Idle Ribosomes in the Presence of an Excess of EFG
We already mentioned that four proteins participate in translation during the elongation phase. Two ofthem, EF-Tu and EF-G, are components of the central activity of the ribosome, the elongation cycle, where in a cycle of reactions the nascent chain is extended by one amino acid aa . EF-Tu brings the aa in the form of aa-tRNA to the decoding centre of the ribosome and EF-G translocates the tRNAs on the ribosome by one codon length reviewed in ref. 20 . These two factors, together with EF-Ts and...
Spoofing and Secrecy
Trust a witness in all matters in which neither his self-interest, his passions, his prejudices, nor the love of the marvellous is strongly concerned. When they are involved, require corroborative evidence in exact proportion to the contravention of probability by the thing testified. When the mother of celebrity abductee Travis Walton was informedthat a UFO had zapped her son with a bolt of lightning and then carried him off into space, she replied incuriously, 'Well, that's the way these...
The Setting of Pseudotachylitic Breccia in Impact Craters
Veins of dark-matrix breccia resembling tectonic pseudotachylite have been described from many impact structures - generally from crater floor rocks, but occasionally from crater rim settings. Such reports are very rare for small, simple bowl-shape craters, and it must be questioned whether any bona fide pseudotachylite friction melt has ever been described from these. For example, the only breccia ever recovered from the crater rim of the Tswaing Pretoria Saltpan meteorite crater that...
Evolution of Selected Characters
The new phylogeny has interesting implications for the evolution of four characters frequently used in considerations of amniote relationships. The tabular-parietal contact has usually been considered to unite embolomeres and seymouriamorphs to diadectomorphs and amniotes Gauthier et al., 1988 , but this character is also present in all lepospondyl groups that have a tabular Figs. 2 and 3 . Therefore, this character is diagnostic of node J embolomeres and batrachomorphs . Of course, the...
The Mastercopy Theory
The leader of the molecular biologists is Harris Bernstein of the University of Arizona. His argument is that sex was invented to repair genes. The first hint of this was the discovery that mutant fruit flies unable to 'repair genes are unable to recombine them, either. Recombination is the essential procedure in sex, the mixing of genes from the two grandparents of the sperm or egg. Knock out genetic repair, and sex stops, too. Bernstein noticed that the tools the cell uses for sex are the...
The Enigma
Birth after birth the line unchanging runs, And fathers live transmitted in their sons Each passing year beholds the unvarying kinds, The same their manners, and the same their minds Till, as erelong successive buds decay, And insect-shoals successive pass away, Increasing wants the pregnant parent vex With the fond wish to form a softer sex Erasmus Darwin, The Temple of Nature Zog the Martian steered her craft carefully into its new orbit and prepared to reenter the hole in the back of the...
222 Continental drift
One of the most dramatic changes that has taken place through geological time see Box 2.2 is continental drift, the movement of continents and oceans relative to each other. The idea that the present layout of continents had not always been the same was suggested in the 19th century, when some geographers noted how the Atlantic coasts of South America and Africa could be fitted together like giant jigsaw pieces. In 1912, Alfred Wegener marshalled a great deal of geological and palaeontological...
Handy Genes
w hile my colleagues and I were digging up the first Tiktaalik in the Arctic in July 2004, Randy Dahn, a researcher in my laboratory, was sweating it out on the South Side of Chicago doing genetic experiments on the embryos of sharks and skates, cousins of stingrays. You've probably seen small black egg cases, known as mermaid's purses, on the beach. Inside the purse once lay an egg with yolk, which developed into an embryonic skate or ray. Over the years, Randy has spent hundreds of hours...
Megaphylls
These are leaves associated with stems that have either a siphonostele or eustele, and are attached to the stem by a petiole Figure 4.7b . Their evolution is thought to be closely linked to the three-dimensional vegetative branching pattern i.e. branches with no sporangia on them of the earliest vascular plants Figure 4.7 a Formation of microphylis according to i the 'Enation theory' Bower, 1935 , which proposed that these 'stem-hugging leaves' evolved from the outgrowth of vascular tissue into...
Thinking like a population geneticist
All scientific fields possess a body of concepts that define their domain as well as a specialized vocabulary used to express these concepts precisely. Population genetics is no different and the entirety of this book is designed to introduce, explain, and demonstrate these concepts and their vocabulary. What may be unique about population genetics among the natural sciences is the way that its practitioners approach questions about the biological world. Population genetics is a dialog between...
Common And Rare Genetic Variants Associated With Venous Thrombosis 81
remains to be done to resolve remaining genetic determinants. Adopting a non-hypothesis-driven approach based on genome-wide association scans is likely to yield additional variants in potentially unexpected genes whose magnitude of effect may be smaller, but whose importance for our ability to define risk and understand disease pathogenesis is likely to be significant. In the normal physiological state a balance exists between pro-coagulant and anticoagulant mechanisms, allowing extravascular...
The Evolution Of Early Land Plants
The first organisms to conquer the land were the green algal ancestors of plants. After being water bound for 500 million years, photosynthetic algae slowly crept onto near-shore rocky surfaces, where they began to adapt anatomical strategies for improving their chances of living outside the ocean. The result was myriad evolutionary changes that led to the domination of plants in all known land environments. Today, there are about 300,000 species of land plants found in terrestrial habitats....
Images
Oil and acrylic on wood, 96 X 120 inches Lystrosaurus and the Permian, 1998 ze 40 Oil and acrylic on wood, 48 X 40 inches Four Interpretations of Page 42 Oil and acrylic on wood, Page 49 Oil and acrylic on wood, Page 62 Oil and acrylic on wood, 32 X 40 inches North America, 1998 Oil and acrylic on wood, 40 X 60 inches La Brea Tar Pit Drawings clockwise from upper left Saber tooth cat American mastodon camel La Brea condor. La Brea tar and lacquer on gessoed paper, 11 X 8.5 inches First...
Rats Teeth
Why, if it is so easy to improve the teeth of rats by artificial selection, did natural selection apparently make such a poor job of it in the first place Surely there is no benefit in tooth decay. Why, if artificial selection is capable of reducing it, didn't natural selection do the same job long ago I can think of two answers, both instructive. The first answer is that the original population that the human selectors used as their raw material consisted not of wild rats but of domesticated...
Nature As The Selecting Agent
Let me draw this chapter, and the previous one, to a conclusion. Selection - in the form of artificial selection by human breeders - can turn a pye-dog into a Pekinese, or a wild cabbage into a cauliflower, in a few centuries. The difference between any two breeds of dog gives us a rough idea of the quantity of evolutionary change that can be achieved in less than a millennium. The next question we should ask is, how many millennia do we have available to us in accounting for the whole history...
6 Stromules
Over the last decade, several important developments have occurred in our understanding of plastids. In addition to major developments in the understanding of molecular processes which occur during plastid development, a subject considered in several other chapters in this book, a renewed consideration of plastid morphology and the dynamic nature of changes in plastid morphology has also taken place. Central to this latter consideration has been the exploitation of green fluorescent protein...
The Discovery of Uranus
it was that night its turn to be discovered. William Herschel describing his discovery of Uranus , very different from any comet I ever read any description of or saw. Nevll Maskelyne, Astronomer Royal. April 1781 On March 13, 1781, amateur astronomer William Herschel discovered a new planet. It was completely unexpected. For as long as anyone could remember, for the thousands of years of recorded history, the solar system ended at Saturn. Mercury, Venus, Mars, Jupiter, Saturn, the Sun. and the...
Results
Analysis 1 The single most parsimonious tree from Beard's 1993b analysis is shown in Figure 2. When Ptilocercus is used to represent Scandentia, the only change in topology is that Scandentia, rather than Chiroptera, is the sister to Primatomorpha Figure 3 . Primatomorpha, however, is still supported Figure 3 . The tree is 52 steps long, the consistency index CI is 0.85, and the retention index RI is 0.83. Analysis 2 A single most parsimonious tree with a length of 64 steps CI 0.77 RI 0.67 was...
Paromomyid Postcranials Gliding and Apatemyid Adaptations
The core of the primatomorph hypothesis developed by Beard 1990, 1991, 1993a,b was the interpretation of paromomyid phalanges and carpal characters as reflecting a gliding adaptation similar to the peculiar finger-gliding adaptation of living colugos dermopterans , and homologous with it. However, several papers since 1990 have raised doubts concerning this interpretation. Krause 1991 questioned the allocation of the isolated middle phalanges to the hand or foot of Phenacolemur however, Beard...
The development of a limb in this case a chicken wing All of the key stages in
To study how this pattern emerges, we need to look at embryos and sometimes interfere with their development to assess what happens when things go wrong. Moreover, we need to look at mutants and at their internal structures and genes, often by making whole mutant populations through careful breeding. Obviously, we cannot study humans in these ways. The challenge for the pioneers in this field was to find the animals that could be useful windows into our own development. The first experimental...
34 Evolutionary trends green algae to land plants
Geological evidence suggests that by 400 million years ago plant evolution had progressed from multicellular eukaryotic organisms that were reliant upon an aquatic medium for survival e.g. green algae , to vascular land plants permanently adapted to a water-deficient habitat. However, what is not so clear from the geological record is the evolutionary pathway that led from the algae to Table 3.1 Classification of the division Chlorophyta green algae in the subkingdom Algae from Bell, 1992 the...