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A tale about tails
While playing Pin the Tail on the Donkey, Sally and Nick get to wondering: What would it be like to have a tail of their own? And how would you pick the best one? Enter the Cat in the Hat. To help the kids choose, he whisks them off to the jungle to see--and try on--a variety of tails that serve different purposes: A monkey's tail that is strong for holding onto branches; a quetzal's tail that is long and colorful for attracting a mate; and a rattlesnake's tail that makes sound as a warning.
Book
The vertebrate tail: a gene playground for evolution
The tail of all vertebrates, regardless of size and anatomical detail, derive from a post-anal extension of the embryo known as the tail bud. Formation, growth and differentiation of this structure are closely associated with the activity of a group of cells that derive from the axial progenitors that build the spinal cord and the muscle-skeletal case of the trunk. Gdf11 activity switches the development of these progenitors from a trunk to a tail bud mode by changing the regulatory network that controls their growth and differentiation potential. Recent work in the mouse indicates that the tail bud regulatory network relies on the interconnected activities of the
Lin28
/
let
-
7
axis and the
Hox13
genes. As this network is likely to be conserved in other mammals, it is possible that the final length and anatomical composition of the adult tail result from the balance between the progenitor-promoting and -repressing activities provided by those genes. This balance might also determine the functional characteristics of the adult tail. Particularly relevant is its regeneration potential, intimately linked to the spinal cord. In mammals, known for their complete inability to regenerate the tail, the spinal cord is removed from the embryonic tail at late stages of development through a
Hox13
-dependent mechanism. In contrast, the tail of salamanders and lizards keep a functional spinal cord that actively guides the tail’s regeneration process. I will argue that the distinct molecular networks controlling tail bud development provided a collection of readily accessible gene networks that were co-opted and combined during evolution either to end the active life of those progenitors or to make them generate the wide diversity of tail shapes and sizes observed among vertebrates.
Journal Article
Tails chasing tails
The reader follows a parade of colorful animals, where the animal on one page is chasing the tail of the animal on the next.
CHILDBOOK
Structure of the siphophage neck–Tail complex suggests that conserved tail tip proteins facilitate receptor binding and tail assembly
Siphophages have a long, flexible, and noncontractile tail that connects to the capsid through a neck. The phage tail is essential for host cell recognition and virus–host cell interactions; moreover, it serves as a channel for genome delivery during infection. However, the in situ high-resolution structure of the neck–tail complex of siphophages remains unknown. Here, we present the structure of the siphophage lambda “wild type,” the most widely used, laboratory-adapted fiberless mutant. The neck–tail complex comprises a channel formed by stacked 12-fold and hexameric rings and a 3-fold symmetrical tip. The interactions among DNA and a total of 246 tail protein molecules forming the tail and neck have been characterized. Structural comparisons of the tail tips, the most diversified region across the lambda and other long-tailed phages or tail-like machines, suggest that their tail tip contains conserved domains, which facilitate tail assembly, receptor binding, cell adsorption, and DNA retaining/releasing. These domains are distributed in different tail tip proteins in different phages or tail-like machines. The side tail fibers are not required for the phage particle to orient itself vertically to the surface of the host cell during attachment.
Journal Article
Understanding Bacteriophage Tail Fiber Interaction with Host Surface Receptor: The Key “Blueprint” for Reprogramming Phage Host Range
Bacteriophages (phages), as natural antibacterial agents, are being rediscovered because of the growing threat of multi- and pan-drug-resistant bacterial pathogens globally. However, with an estimated 1031 phages on the planet, finding the right phage to recognize a specific bacterial host is like looking for a needle in a trillion haystacks. The host range of a phage is primarily determined by phage tail fibers (or spikes), which initially mediate reversible and specific recognition and adsorption by susceptible bacteria. Recent significant advances at single-molecule and atomic levels have begun to unravel the structural organization of tail fibers and underlying mechanisms of phage–host interactions. Here, we discuss the molecular mechanisms and models of the tail fibers of the well-characterized T4 phage’s interaction with host surface receptors. Structure–function knowledge of tail fibers will pave the way for reprogramming phage host range and will bring future benefits through more-effective phage therapy in medicine. Furthermore, the design strategies of tail fiber engineering are briefly summarized, including machine-learning-assisted engineering inspired by the increasingly enormous amount of phage genetic information.
Journal Article
The long and short tale of Colo and Ruff
\"Colo the cougar and her friend Ruff jump and play together, but they find that Ruff can't jump nearly as far as Colo. Ruff doesn't have a long, swishy tail like Colo does, to provide balance on long leaps. Ruff is a bobcat and his tail is much shorter. He is sure that something is wrong with him. The sympathetic Colo suggests that they go find a tail that Ruff would like better, so off they go. As the two kittens explore the variety of tails worn by other animals, they make the best discovery of all\"-- Provided by publisher.
Book
Amputation-induced reactive oxygen species are required for successful Xenopus tadpole tail regeneration
Xenopus laevis
and
tropicalis
tadpoles display incredible regenerative capacity of their tail. Amaya and colleagues find that tadpole tail amputation induces the production of reactive oxygen species (ROS) to induce cell proliferation and regeneration, through activation of the Wnt/β-catenin and Fgf20 signalling pathways.
Understanding the molecular mechanisms that promote successful tissue regeneration is critical for continued advancements in regenerative medicine. Vertebrate amphibian tadpoles of the species
Xenopus laevis
and
Xenopus tropicalis
have remarkable abilities to regenerate their tails following amputation
1
,
2
, through the coordinated activity of numerous growth factor signalling pathways, including the Wnt, Fgf, Bmp, Notch and TGF-β pathways
3
,
4
,
5
,
6
. Little is known, however, about the events that act upstream of these signalling pathways following injury. Here, we show that
Xenopus
tadpole tail amputation induces a sustained production of reactive oxygen species (ROS) during tail regeneration. Lowering ROS levels, using pharmacological or genetic approaches, reduces the level of cell proliferation and impairs tail regeneration. Genetic rescue experiments restored both ROS production and the initiation of the regenerative response. Sustained increased ROS levels are required for Wnt/β-catenin signalling and the activation of one of its main downstream targets,
fgf20
(ref.
7
), which, in turn, is essential for proper tail regeneration. These findings demonstrate that injury-induced ROS production is an important regulator of tissue regeneration.
Journal Article
Tail-propelled aquatic locomotion in a theropod dinosaur
In recent decades, intensive research on non-avian dinosaurs has strongly suggested that these animals were restricted to terrestrial environments
1
. Historical proposals that some groups, such as sauropods and hadrosaurs, lived in aquatic environments
2
,
3
were abandoned decades ago
4
,
5
–
6
. It has recently been argued that at least some of the spinosaurids—an unusual group of large-bodied theropods of the Cretaceous era—were semi-aquatic
7
,
8
, but this idea has been challenged on anatomical, biomechanical and taphonomic grounds, and remains controversial
9
,
10
–
11
. Here we present unambiguous evidence for an aquatic propulsive structure in a dinosaur, the giant theropod
Spinosaurus aegyptiacus
7
,
12
. This dinosaur has a tail with an unexpected and unique shape that consists of extremely tall neural spines and elongate chevrons, which forms a large, flexible fin-like organ capable of extensive lateral excursion. Using a robotic flapping apparatus to measure undulatory forces in physical models of different tail shapes, we show that the tail shape of
Spinosaurus
produces greater thrust and efficiency in water than the tail shapes of terrestrial dinosaurs and that these measures of performance are more comparable to those of extant aquatic vertebrates that use vertically expanded tails to generate forward propulsion while swimming. These results are consistent with the suite of adaptations for an aquatic lifestyle and piscivorous diet that have previously been documented for
Spinosaurus
7
,
13
,
14
. Although developed to a lesser degree, aquatic adaptations are also found in other members of the spinosaurid clade
15
,
16
, which had a near-global distribution and a stratigraphic range of more than 50 million years
14
, pointing to a substantial invasion of aquatic environments by dinosaurs.
Discovery that the giant theropod dinosaur
Spinosaurus
has a large flexible tail indicates that it was primarily aquatic and swam in a similar manner to extant tail-propelled aquatic vertebrates.
Journal Article