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| A cross-section through a shell showing the periodically layered nacre on top of a prismatic shell structure. |
It's so easy, anyone can do it. All it takes is an open mind and an interest in truth.
Opposites attract: scientists discover how mother-of-pearl self-assembles into a perfect structure — TU Dresden
The first of these papers is from a combined German and French team from the B CUBE - Center for Molecular Bioengineering at Technische Universität, Dresden, Germany, and European Synchrotron Radiation Facility (ESRF) in Grenoble, France. They have shown how the highly organised perfection in the arrangement of molecules that give mother of pearl or nacre, its colour and lustre is an emergent property from the chaotic production of the molecules from which it is made, under nothing more than the operation of chemistry and physics, with no magic input required to explain it. Creationist dogma, of course, insists that order cannot come from choas, without intelligent input because this would allegedly contravene the Second Law of Thermodynamics.
The press release from Technische Universität, Dresden explains:
Mother-of-pearl, also known as nacre, is an incredibly strong biomaterial forming the shell of some mollusks. Its strength and beauty comes from its remarkably regular and uniform architecture. Until now, it was unclear how this intricate structure could be built by a multitude of single cells, all secreting materials at different locations at the same time. In a new study published in Nature Physics, researchers from the B CUBE - Center for Molecular Bioengineering at TU Dresden and European Synchrotron Radiation Facility (ESRF) in Grenoble describe, for the first time, that structural defects in self-assembling nacre attract and cancel each other out, eventually leading to a perfect periodic structure.Note particularly that last sentence with its reference to 'thermodynamic principles'. Clearly, the claim that order cannot emerge from chaos without violating a basic law of science is either a deliberate misrepresentation of science or comes from a failure to understand it. This has been pointed out so many times and so frequently to Creationists that its difficult to avoid the conclusion that this misrepresentation as anythign other than a deliberate attempt at deception, intended to fool people into believing falsehoods.
Mollusks build shells to protect their soft tissues from predators. Nacre, also known as the mother of pearl, has an intricate, highly regular structure that makes it an incredibly strong material. Depending on the species, nacres can reach tens of centimeters in length. No matter the size, each nacre is built from materials deposited by a multitude of single cells at multiple different locations at the same time. How exactly this highly periodic and uniform structure emerges from the initial disorder was unknown until now.
Simulated evolution of the phase field at the front of the growing structure, obtained using the Kuramoto model. Time in the video represents the growth of the structure.
Nacre formation starts uncoordinated with the cells depositing the material simultaneously at different locations. Not surprisingly, the early nacre structure is not very regular. At this point, it is full of defects. “In the very beginning, the layered mineral-organic tissue is full of structural faults that propagate through a number of layers like a helix. In fact, they look like a spiral staircase, having either right-handed or left-handed orientation,” says Dr. Igor Zlotnikov, research group leader at the B CUBE – Center for Molecular Bioengineering at TU Dresden. “The role of these defects in forming such a periodic tissue has never been established. On the other hand, the mature nacre is defect-free, with a regular, uniform structure. How could perfection emerge from such disorder?”
The researchers from the Zlotnikov group collaborated with the European Synchrotron Radiation Facility (ESRF) in Grenoble to take a very detailed look at the internal structure of the early and mature nacre. Using synchrotron-based holographic X-ray nano-tomography the researchers could capture the growth of nacre over time. “Nacre is an extremely fine structure, having organic features below 50 nm in size. Beamline ID16A at the ESRF provided us with an unprecedented capability to visualize nacre in three-dimensions,” explains Dr. Zlotnikov. “The combination of electron dense and highly periodical inorganic platelets with delicate and slender organic interfaces makes nacre a challenging structure to image. Cryogenic imaging helped us to obtain the resolving power we needed,” explains Dr. Pacureanu from the X-ray Nanoprobe group at the ESRF.
The analysis of data was quite a challenge. The researchers developed a segmentation algorithm using neural networks and trained it to separate different layers of nacre. In this way, they were able to follow what happens to the structural defects as nacre grows.
The behavior of structural defects in a growing nacre was surprising. Defects of opposite screw direction were attracted to each other from vast distances. The right-handed and left-handed defects moved through the structure, until they met, and cancelled each other out. These events led to a tissue-wide synchronization. Over time, it allowed the structure to develop into a perfectly regular and defect-free.
Periodic structures similar to nacre are produced by many different animal species. The researchers think that the newly discovered mechanism could drive not only the formation of nacre but also other biogenic structures.
Dr. Igor Zlotnikov is a leader of a multidisciplinary group at the B CUBE, TU Dresden. The group studies the interplay between physics of materials and cellular control. The Zlotnikov group implements state-of-the-art techniques from a large spectrum of fields in life and physical sciences to address the fundamental question of how the nature uses thermodynamic principles to generate complex structures.
The team published their findings in the journal Nature Physics a couple of days ago, sadly behind and expensive paywall.
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| Native bittering fish, Tanakia lanceolata Freshwater fish distributed in Japan, South Korea, and China. Listed as near threatened in Japanese Red List. Credit : Hiroki Hata (Ehime University) |
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| Unionid mussel, Pronodularia japanensis Freshwater unionid species endemic in Japan. Credit : Hiroki Hata (Ehime University) |
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| Excessive crowding of native and invasive bitterling fishes of a mussel Excessive crowding of a native Tanakia lanceolata (orange fin) and invasive Tanakia limbata (olive brown body) of a mussel, Pronodularia japanensis, seen at the bottom center in the image. Credit : Hiroki Hata (Ehime University) |
The second publication, by a Japanese team led by Hiroki Hata of the Graduate School of Science and Engineering, Ehime University, Matsuyama, Japan, shows the difference between an intelligently-designed reproductive strategy such as would be expected of an intelligent, omniscient designer, and that produced by a natural process with no foresight, and no ability to learn from past failures or abandon a failing strategy and start again with a better one. The facts, of course, support the latter view because that's what produced the reproductive strategy with no indication of intelligence or planning involved.
The reproductive strategy is that of the small member of the carp family, the bitterling, which lays its eggs in the gills of fresh-water mussels. This strategy is assumed to have evolved because it gives the eggs protection from predators and so ensures a greater breading success than would otherwise have been the case with eggs deposited in the river bed.
The close association between the bitterling and the mussels and the reason the mussels have not evolved a strategy for rejecting the eggs and the fish have not evolved a strategy for rejecting the juvenile mussels, is because the mussels are also dependent on the presence of fish such as the bitterling for their own reproductive strategy, so anything which improved the survival of bitterling also improved the survival of the mussels and vice versa. One of the problems facing species that live in rivers is that, unless they can overcome the tendency to be carried downstream by the current, they will all end up being flushed out of the river. Mussels use fish to overcome this problem by producing a parasitic juvenile form which attaches to the gills of fish such as the bitterling to aid in their dispersal upstream. Bitterling and mussels have evolved this mutualism because cooperation produces more offspring, and any cost is more than compensated for by the benefits.
But, as the authors of this paper found, a strategy which is dependent on the existence of another species is also at risk from anything which might affect the survival of that species. Mussels and bitterling have both headed down a path that could lead to extinction and there is no way back. As the Ehime University press release, Risk of extinction cascades from freshwater mussels to a bitterling fish, explains:
These findings were published in the journal Freshwater Biology.Decline of unionid mussels heightens hybridisation of native and introduced bitterling fish
Reproduction of native and invasive bitterling fishes and their hybridisation was studied in Japan. We collected mussels in which these bitterlings lay their eggs, kept them in aquaria, collected eggs/larvae ejected from mussels, and genotyped them. We found that hybrids occurred when local mussel density was low. The rapid decline of the host mussels and artificial introduction of an invasive congener interacted to cause the rapid decline of a native fish.
Bitterling fishes (Subfamily: Acheilognathinae) spawn in the gills of living freshwater mussels obligately depending on the mussels for reproduction. On the Matsuyama Plain, Japan, populations of unionid mussels—Pronodularia japanensis, Nodularia douglasiae, and Sinanodonta lauta—have decreased rapidly over the past 30 years. Simultaneously, the population of a native bitterling fish, Tanakia lanceolata, which depends on the three unionids as a breeding substrate, has decreased. Furthermore, a congeneric bitterling, Tanakia limbata, has been artificially introduced, and hybridisation and genetic introgression occur between them. Here, we surveyed the reproduction and occurrence of hybridisation between native and invasive species of bitterling fishes. We collected mussels in which these bitterlings lay their eggs, kept them separately in aquaria, collected eggs and larvae ejected from the mussels, and genotyped them using six microsatellite markers and mitochondrial cytochrome b sequences.
The introduced T. limbata was more abundant, had a longer breeding period, and produced more juveniles than the native T. lanceolata. Hybrids between the two species occurred frequently, and in total 101 of the 837 juveniles genotyped were hybrids. The density of P. japanensis was low, at most 0.42 individuals/m2. Nodularia douglasiae and S. lauta have nearly or totally disappeared from these sites. Hybrid clutches of the Tanakia species occurred more frequently where the local density of P. japanensis was low. The mussels were apparently overused and used simultaneously by three species of bitterlings.
The decline of freshwater unionid populations has heightened hybridisation of native and invasive bitterling fishes by increasing the competition for a breeding substrate. We showed that a rapid decline of host mussel species and an introduction of an invasive congener have interacted to cause a rapid decline of native bitterling fish. The degradation of habitat and the introduction of invasive species interact to cause a cascade of extinctions in the native species. In our study, obligate parasite species are threatened because the host species are disappearing, resulting in a serious threat of coextinction.
No intelligent designer, let alone an omniscient one who understands the consequences, pitfalls and limitations of its design would come up with a delicately balanced coexistent strategy that, if the dynamics are altered slightly can result in coextinction. As we so often see from a close look at biology, there is no evidence for intelligent involvement anywhere and abundant evidence of its absence.Abstract
- Bitterling fishes (Subfamily: Acheilognathinae) spawn in the gills of living freshwater mussels and obligately depend on the mussels for reproduction. On the Matsuyama Plain, Japan, populations of unionid mussels—Pronodularia japanensis, Nodularia douglasiae, and Sinanodonta lauta—have decreased rapidly over the past 30 years. Simultaneously, the population of a native bitterling fish, Tanakia lanceolata, which depends on the three unionids as a breeding substrate, has decreased. Furthermore, a congeneric bitterling, Tanakia limbata, has been artificially introduced, and hybridisation and genetic introgression occur between them. Here, we hypothesised that decline of the unionids has enhanced this invasive hybridisation through competition for the breeding substrate.
- Three study sites were set in three streams on the Matsuyama Plain. We collected adult bitterling fishes (native T. lanceolata, introduced T. limbata, and foreign Rhodeus ocellatus ocellatus) once a week from April to October 2013 to measure their densities in streams and to examine seasonal differences in female ovipositor length, which elongates in the breeding season. Simultaneously, we set quadrats and captured unionids and measured environmental conditions. Each unionid individual was kept separately in its own aquarium to collect ejected bitterling eggs/larvae. Tanakia eggs and larvae were genotyped using six microsatellite markers and the mitochondrial cytochrome b gene.
- Introduced T. limbata was more abundant, had a longer breeding period, and produced more juveniles than native T. lanceolata. Hybrids between the two species occurred at all sites, and in total 101 of the 837 juveniles genotyped were hybrids. The density of P. japanensis was low, at most 0.42 individuals/m2. Nodularia douglasiae and S. lauta have nearly or totally disappeared from these sites. Hybrid clutches of Tanakia species occurred more frequently where the local density of P. japanensis was low. Mussels were apparently overused and used simultaneously by three species of bitterlings.
- Decline of freshwater unionid populations has enhanced hybridisation of native and invasive bitterling fishes through increasing competition for breeding substrate. We showed that rapid decline of host mussel species and introduction of an invasive congener have interacted to cause a rapid decline of native bitterling fish.
- Degradation of habitat and the introduction of invasive species interact to cause a cascade of extinctions in native species. In our study, obligate parasite species are threatened because the host species are disappearing, which means there is a serious threat of coextinction.
And yet another plank of creationist dogma is refuted by the facts as science reveals them.
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