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Notes and News

ISCA Kolkata Chapter felicitates Dr. ManojK Chakrabarti, General President Elect,

ISCA

Indian Science Congress Association, Kolkata Chapterorganized a programme to felicitate Dr. Manoj K.

Chakrabarti, Ph.D., FAScT, FNASc, ICMR EmeritusMedical Scientist and Former Director-in-Charge,NICED(an ICMR Institute), Kolkata and also an ISNAcouncil member, on May 19, 2017 at the Department ofPhysiology, University of Calcutta, for being elected asGeneral President of Indian Science Congress Associationfor 2018-19. A special lecture was organized as a part ofthe felicitation programme and Professor DebasishBandyopadhyay, Head, Department of Physiology,University of Calcutta was the invited speaker.

Professor A M Chandra, immediate past Convener ofISCA delivered the welcome address. Professor TusharkantiGhosh, Convener, ISCA Kolkata Chapter, in his speechmentioned about the unique accomplishment of Dr.Chakrabarti of becoming the General President from thePhysiology fraternity, after a gap of more than threedecades, after Dr. A. S. Paintal, FRS, in 1985. As Dr.Chakrabarti is also the Chairperson of the ISCA KolkataChapter, it was also a moment of celebration for membersof the Kolkata Chapter, especially in view of the fact thatno scientist from Kolkata adorned the high office of thegeneral President of ISCA after Dr. S. C. Pakrashi. Dr.B.P. Chatterjee, Past General Secretary, ISCA talked aboutthe Dr. Chakrabarti’s association with ISCA in differentcapacities like member of the council, General Secretaryand so on. Professor Debasish Bandyopadhyay, Head,Department of Physiology, University of Calcutta referredabout the continued association Dr. Chakrabarti maintainedwith his almamater- the Department of Physiology,University of Calcutta - inspite of his umpteen commitmentsas scientist, research institute administrator and shoulderingof huge responsibility at ISCA.

In his felicitation speech Dr. Manoj KumarChakrabarti, General President-Elect outlined his vision andplans for further improvement of the activities of more thana century old Indian Science Congress Association as wellas the annual science congress event.

In the second half of the programme, ProfessorDebasish Bandyopadhyay, Head, Department of Physiologydelivered a talk on ‘Isoproterenol Induced Alteration inCardiac Pyruvate Dehydrogenase and Some of The Kreb’sCycle Enzymes are Protected by Melatonin: Mechanismand Therapeutic Relevance’. His talk delivered in Bengali,was enjoyed by in audience which includes large numberof post graduate and research students of the department.The programme was attended among others by ProfessorT K Bose, past Sectional President, Medical Science, IndianScience Congress and Professor and Head, Department ofForensic Medicine, N.R.S. Medical College, Kolkata, Dr.Shankarashis Mukherjee, Department of Physiology,University of Calcutta, Professor (Retired) Bithi Sarkar, Dr.Triveni Krishnan, Scientist F, NICED, Kolkata. After thelecture, Professor Tusharkanti Ghosh offered formal voteof thanks to all concerned.

Neepa Banerjee, Surjani Chatterjee, SatabdiBhattacharjee and Shankarashis Mukherjee*

Human Performance Analytics and Facilitation UnitDepartment of Physiology

University of Calcutta, Kolkata, India*msasish@yahoo.co.in

Symposium on Fish Immunology atICAR-CIFRI, Barrackpore

Preventive and prophylactic measures to minimizelosses due to diseases in aquaculture can be effectively

carried out with the basic information on the onset of innateand acquired immunity of the fish species underconsideration {Ref: Ellis, A. E. 1977. DevelopmentalImmunobiology (Eds. J. B. Solomon and I. D. Horton),Academic Press, London, Vol. 61: 225-331pp}. Aiming atdeliberations on recent advances in fish immunology, the‘Satellite Symposium on Fish Immunology’ was organizedat ICAR-Central Inland Fisheries Research Institute,Barrackpore, Kolkata on June 11, 2017. In the Symposium,the first ‘Prof. Anthony Ellis Memorial Lecture’ wasdelivered by Dr. S. C. Mukherjee, Former Joint Director,ICAR-Central Institute of Fisheries Education, Mumbai onthe topic ‘Immune system in fishes’. Dr B. K. Das, Director,ICAR-CIFRI in his inaugural and introductory address

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explained that Prof. Anthony E. Ellis was a distinguishedscientist in the discipline of fish immunology andvaccination. He worked at Fisheries Research Services ofMarine Laboratory, Aberdeen, Scotland, and died in 2012due to colon cancer.

Dr. (Mrs.) K. Samantaray, Emeritus Scientist, ICAR-CIFA, Bhubaneswar; Former Director, College of Fisheries,Rangeilunda, Orissa and eminent fish nutritionist mentionedthat we can prevent diseases in fishes through nutritionalmodulation. Supplementary diet and nutritional factorsinfluence the immune responses in fishes, thereby regulatinghealth and disease outcomes. Investigation is needed uponhow diet modulates the fish gut microbiome and mucosalimmune responses. Vaccination enhances survival rate andprofitability in aquaculture when used in combination withseveral factors which are necessary to guarantee the highestpossible survival rate; one of such factors is good nutrition.Dr. Dilip Kumar, Former Director, ICAR-CIFE, Mumbaiexplained that diseases are the greatest deterrent insustainable aquaculture. Consequence of disease in tigershrimp (industrial) aquaculture is loss of money worthmillion dollars; whereas disease in major carps inflictsmillions of rural livelihoods. He emphasized on finfish andshellfish vaccination as prophylactic measure, in connectionwith prevention and outbreak of diseases, and discussedhis experiences of 1985-1986 in eastern Europe on massvaccination of cultivable economically-important fishes.Dr. K. H. Rahaman, President, Zoological Society ofBangladesh and Dr. Mostafizur Rahaman, Addl. DirectorGeneral, Department of Fisheries, Government ofBangladesh also spoke in the inaugural session.

Dr. Mukherjee in his presentation explained aboutinnate immunity (biological wisdom) as first and secondline of defence and adaptive immunity (which may take 4-5 weeks in fishes) as third line of defence, importance ofinnate elimination of infection (body reactinginstantaneously within 4-6 hours), molecular patterns thatare associated with pathogenic agents and with host’s owndanger signals, C-reactive protein, entry route of pathogens,substances involved in natural resistance, cytokine protein,innate communication with the acquired system, humoralinnate parameters {growth inhibitors, iron binding(transferin), lysozymes, agglutinins, natural antibodies,cytokines, antibacterial peptides}, importance of AlternativeComplementary Pathway, roles of NK cells, phagocytes,cytotoxic cells and helper T lymphocytes, origin oferythrocytes and different leucocytes from haematopoieticstem cells, commonly used immunostimulants in fish farm,modifiers of immunity in fishes (genetic traits, seasonalfactors, temperature, pollution, stress, disease, vaccination,

probiotics, immunostimulants), mechanisms of innate andadaptive immunity.

Dr. Mukherjee explained that when fish gut enzymesare fermented, it harms skin mucosa and provide entry topathogens. He discussed about temperature affectingimmune responses; for warmwater carps, expression ofmaximum immune responsiveness appears at ≤ 15°C andthe same for coldwater salmonids at ≤ 4°C. Temperatureless than 15°C for warmwater carps and less than 4°C forsalmonids is opened for infection. Low temperaturesuppresses the ability of T cells to produce macrophageinhibiting factor, hence impairing important cell-mediatedimmune mechanisms. He discussed about dose of antigenadministered and level of antibody production,immunogenicity of different antigens differing between fishspecies (e.g., horse erythrocytes are good antigen for winterflounder and anti-horse RBC antibodies are producedquickly in flounder, whereas sheep RBC not as good ashorse erythrocytes in flounder but is good antigen forcommercially-important major carps), production ofmemory cells; he explained why children infected bymeasles and chicken box do not get infected second time.In the end, Dr. Mukherjee discussed about routes ofadministration of antigen as vaccine, immersion vaccination,sea bass showing late appearance of complement proteinat 15 days post hatching (dph) and specific parameters,i.e., IgM production at 50 dph; whereas major carps showearly appearance of innate immune response at 1 dph andadaptive immune response at 4 dph. Thus it is easier tovaccinate the carps.

Dr. T. J. Abraham, Professor at Department of AquaticAnimal Health, Faculty of Fishery Sciences, WBUAFS,Kolkata made his presentation on ‘Immune effector andendocrine regulatory activities of the commercially-important catfish Pangasius pangasius (Hamilton) asaffected by Edwardsiella tarda challenge and temperature’.Symptoms of Edwardsiellosis include blood red spots onbody of fish, yellow coloured fluid accumulation inintraperitoneal cavity, smell of rotten egg is felt when fishis cut open. Dr Abraham described a time and temperaturedependent kinetic study on changes in immune effectoractivities of P. pangasius administered with a sub-lethaldose (2.17×107 cells/fish) of E. tarda, he also assessed theendocrine regulatory activities (serum cortisol, serum IGF-1, IGFBP-1) of E. tarda challenged P. pangasius.

Dr. Abraham estimated certain non-specific immuneresponse parameters, like serum lysozyme content,determination of serum myeloperoxidase, ceruloplasmin andanti-protease activities, respiratory oxidative burst activityby neutrophils, production of nitric oxide (NO) by

g

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macrophages; and specific immune parameters likeseroreactivity and in-vitro lymphocyte proliferation by headkidney leucocytes. He discussed variations in theseparameters during winter and summer. P. pangasius canrespond to the stress caused by E. tarda challenge bysecreting significantly higher levels of cortisol and IGFBP-1, and impede the endocrine network by decreasing IGF-llevel. He discussed that E. tarda infection has impacts onrelative disease levels of this catfish via regulation of theGH/IGF-I/IGFBP-1 network. He suggested that inhatcheries, only those specific pathogen resistant (SPR) andspecific pathogen tolerant (SPT) P. pangasius broodersmust be maintained which possess lysozyme content above275 Units/ml. It will be wise to avoid P. pangasius culturein farm ponds during winter months as the pathogenicbacterium has immunosuppressive action on the fish.Immunostimulant-supplemented feeds should be used forthis catfish at least two months prior to winter and duringwinter.

Dr. M. Samanta, Principal Scientist at ICAR-CIFA,Bhubaneswar spoke on “Critical roles of the innate immunereceptors signaling pathway in activating adaptive immunityin fish, wrt TLR/NLR signaling pathways”. Toll-likereceptors and nucleotide-binding and oligomerizationdomain-like receptors, which govern innate immunity andalso augment humoral immunity, play key role in pathogenassociated molecular patterns (PAMPs). An immediateactivation of innate immune response by the host relies onthe detection of conserved microbial motifs, which arePAMPs. In rohu Labeo rohita, various TLRs and NLRshave been identified and their molecular structuresdetermined. The cytoplasmic pattern recognitionreceptor NOD-1 senses a wide range of bacteria and virusesor their products in fishes, and plays a key role in inducinginnate immunity. In plants and animals, various families ofpattern recognition receptors (PRRs) recognize PAMPs andactivate signaling to induce innate immunity. TLRs andNLRs are included under signaling PRRs. Dr. Samanta hasinvestigated NOD-1 and NOD-2 receptors in L. rohita andCirrhinus mrigala and their downstream signaling moleculeRICK following ligand stimulation and Gram positive andGram negative bacterial infections.

Dr. Gayatri Tripathi, Senior Scientist at AquaticAnimal Health Management Division, ICAR-CIFE, Mumbaimade her presentation on ‘Stem cell research andpluripotency of stem cells’. Embryonic stem cells arederived from the inner cell mass of embryo at blastula stageand possess the capacity to divide for long periods,retaining their ability to make all cell types (pluripotency)within the organism. An embryonic cell line, established

from gastrula-stage embryos of fish can be used for thestudy of infectious viruses in fish and for developing cellmodels for screening immune-related functional genes insame fish species, Dr Tripathi explained. Stem cells havethe potential for self-renewal and differentiation; fishmodels as lower vertebrates represent an importantreference to study the conserved mechanisms underlyingself-renewal and differentiation.

Dr. Syed M. Istiak, Chief Advisor, Deep Sea FishersLtd., Bangladesh made his presentation on ‘One motherone tank – a way to produce WSSV-free shrimp post larvae(PL)’. In shrimp culture ponds, WSSV is one of the mostdevastating viruses infecting penaeid shrimp. Post-larvae ofthe commercially important shrimp P. monodon producedin hatcheries must be certified, and are expected to be freeof certain pathogenic viruses like WSSV. Recently in ashrimp hatchery at Cox’s Bazar town in Bangladesh, asystem has been constructed to produce safe and securedPL using one WSSV-negative brood mother keeping intoone spawning tank (500lit). Dr. B. Kalita, AssociateProfessor, College of Fisheries, Assam AgriculturalUniversity, Raha town, Assam spoke on ‘Histogenesis (i.e.,differentiation of cells into specialized tissues and organsduring growth) and morphology of lymphoid organs inIndian major carps’. Proper understanding of the histologyof the lymphatic tissues in fish helps us to understand thephysiology and immunology of the lymphoid system. Dr.Kalita also discussed about his research on immersionimmunization; fry of IMC were immunized at 4 and 8weeks post hatching by direct immersion in a suspension(108 cells/ml) of heat inactivated Aeromonas hydrophila.Ability of the IMC fry to elicit humoral and protectiveresponses against A. hydrophila was tested. In the end, Dr.B. K. Das discussed about the contributions of fishimmunologists, pathologists, microbiologists andbiotechnologists, both working in and who worked in ICARresearch institutions and fisheries colleges in different statesin India, their research achievements and immunodiagnostickits developed for diseases in finfishes and shrimps.

Subrato GhoshFishery Extension Officer

FFDA, South 24 Parganas, West Bengal

WOW! Planet 10 Round the Corner

We learnt during our school days that there are nineplanets in the solar system – Mercury, Venus, Earth,

Mars, Jupiter, Saturn, Uranus, Neptune and Pluto, workingoutwards from the sun. Subsequently, however, it was

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discovered that there are many small, icy objects like Plutoin the region known as the Kuiper belt which starts beyondNeptune and covers up to 55 AU (i.e. 55 times furtherfrom the sun than the earth is). The InternationalAstronomical Union took a monumental decision in 2006to declassify Pluto as a “Dwarf Planet”. Any object in theKuiper belt is not considered as a planet any more. Thenumber of planets in the solar system was thus reduced toeight.

But the situation seemed to change last year. Batyginand Brown of Caltech, USA claimed last year(Astronomical Journal, 152 (2), 2016) the existence of anew solar planet, named Planet 9, with a mass comparableto that of Neptune, nearly 10 times that of earth and about5,000 times that of Pluto. This new planet is believed toorbit around the sun at about 700 AU from it.

Now there is another claim. In a paper to be publishedshortly (Astronomical Journal, Draft version, June 15,2017), Kathryn Volk and Renu Malhotra of the Universityof Arizona, Tucson, USA suggested the existence of anotherplanet of the size of Mars and orbiting round the sun atthe tail end of the Kuiper belt, viz. 30-55 AU. They haveuncovered signs of weird warps in the orbits of distantKuiper belt objects (KBOs), based on which they madetheir claim.

The claims for both Plane 9 and Planet 10 are basedon the same principle which is as follows. All the solarplanets orbit round the sun in roughly the same plane. Thismean plane of the solar system is also known as the‘invariable plane’. But the smaller KBOs are far enoughfrom the gravitational influence of the giant planets. As aresult, their gravitational interactions nudge them from thisplane to avoid collisions, forcing them to orbit round thesun at angles to this plane. For any KBO, this angle, alsoknown as ‘inclination’, can be predicted from calculationsthat use a host of advanced technologies, including surveysof the sky. If these calculations do not match the real pathof the KBO, it suggests that there may be another object,a large body (near the end or outside the Kuiper belt)whose gravity is causing the observed deviation in themovement of the KBO.

For the distant Kuiper belt objects (50-80 AU), themean plane is expected to be close to the invariable plane.But as per the refined measurements and calculations ofVolk and Malhotra, the deviation (ca. 9°) of the mean planefrom the invariable plane was large and statisticallysignificant. As one possible explanation for this observation,they suggested the possible existence of a 10th planet ofthe size of Mars at around the tail end of the Kuiper belt.

Batygin, one of the discoverers of Planet 9, was, however,sceptical and said, “given its mass and distance, it shouldbe bright enough to have been seen by now, although itcould be obscured by the bright galactic centre.”Alessandro Morbidelli at the Côte d’Azur Observatory inNice, France voiced a similar doubt, “I am dubious that aplanet so close and so bright would have remainedunnoticed.” But Volk seems to be pretty confident abouttheir finding. She said, “It would have to be quite a flukefor this to not be a real effect.” The existence of bothPlanets 9 and 10 remain to be confirmed.

Professor Manas Chakrabarty, FRSCFormerly, Department of Chemistry

Bose Institute, Kolkata

Astronomers Capture the Firstever“Image” of Dark Matter

It has been known since early 19th century that all matterthat we see around – the Earth, Sun, stars and galaxies

– is made up of atoms comprising protons, neutrons andelectrons. But 20th century brought a surprising discoverythat ordinary, or baryonic, matter that makes up the visibleuniverse comprises less than 5 percent of the mass of theuniverse. The rest is made up of unknown entities dubbeddark matter and dark energy. Dark matter is an invisiblesubstance that makes up 25 percent of the universe, anddark energy is a force that repels gravity and makes upthe rest 70 percent. Although dark matter makes up about25 percent of the universe, it doesn’t shine, reflect, orinteract with light in any way, so it is difficult to study.The only way to study it is by observing its gravitationaleffect.

What dark matter is actually made of remains amystery, and finding evidence of something that cannot beseen is a daunting task. This is mainly because it does notinteract with baryonic matter and is completely invisibleto light and other forms of electromagnetic radiation.Previously, the closest proof of dark matter was itsgravitational effects, but now, researchers have somethingeven better: a composite picture that proves that galaxiesare indeed connected by dark matter. By combiningphotographs of more than 23,000 galaxy pairs located 4.5billion light-years away, taken over several years,researchers at the University of Waterloo in Ontario,Canada have been able to capture the first composite imageof a dark matter bridge that connects galaxies together(Monthly Notices of the Royal Astronomical Society, 1March 2017 | DOI: 10.1093/mnras/stx517). According to

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The Science Behind ShoelacesComing Untied

Many of us must have experienced accidental untyingof our shoelaces while running or playing in our

childhood. Athletes and those engaged in sports activitiesalso face the problem of shoelaces spontaneously cominguntied, often at the most inopportune time. But despite theproblem being so common, little was known and even lesswas documented about the physical mechanisms responsiblefor this persistent problem, although there have been someinteresting observations. For example, it has been foundthat a shoelace knot that often came loose very quicklywhen walking (typically within 15-20 metres) did not failwhen the leg was simply swung back and forth a similarnumber of times, while sitting at one place withoutstomping the foot on ground. Again, simply stomping thefoot on the ground the same number of times withoutswinging the legs also did not lead to untying. It was clearthat for the shoelace knot to come untied both swinging ofthe feet and stomping on the ground was necessary. In otherwords, it involved interplay between the forces generatedin the swing and stomping of feet during the walking orrunning motion. Recently, a team of engineers of theUniversity of California at Berkeley have come out with ascientific explanation of the phenomenon. Their studysuggests that a combination of stomping and whippingforces acts like an invisible hand, loosening the knot andthen tugging on the free ends of the laces until the wholething unravels (Proceeding of the Royal Society A:Mathematical, Physical and Engineering Science, 12 April,2017 | DOI: 10.1098/rspa.2016.0770).

A sportsman tying his shoelaces in the field.

To find out why even the best knots fail, OliverO’Reilly, a mechanical engineer at the University ofCalifornia, Berkeley, and colleagues studied the problemin a series of experiments that involved filming one of theircolleagues with a high-speed camera as she ran on a

the researchers Mike Hudson, a professor of astronomy,and Seth Epps at the University of Waterloo, the compositeimage confirms predictions that galaxies across the universeare tied together through a cosmic web connected by darkmatter that has until now remained unobservable. The effectwas measured in images from a multiyear sky survey atthe Canada-France-Hawaii Telescope on Mauna KeaMountain in Hawaii.

False colour image showing one of the dark matter bridges between,two galaxies visible as large white dots. (Image credit: University ofWaterloo)

For decades, in their search for dark matter, scientistshave tracked hints of a threadlike structure that ties togethergalaxies across the universe. Theories, computer models,and indirect observations have indicated that there is acosmic web of dark matter that connects galaxies andconstitutes the largescale structure of the cosmos. But whilethe filaments that make up this web are massive, darkmatter is incredibly difficult to observe.

The key to the recent success was the clever use of aphenomenon called weak gravitational lensing. Althoughdark matter is invisible, it does have mass and that meansit deflects light ever so slightly, as predicted by Einstein’sgeneral relativity theory. So, by observing the way lightfrom distant galaxies is distorted, it is possible to map thedistribution of mass between the Earth and the galaxies.Comparing this to the visible matter of galaxies allowsastronomers to map the presence of dark matter.

Explaining the image Hudson says, “For decades,researchers have been predicting the existence of dark-matter filaments between galaxies that act like a web-likesuperstructure connecting galaxies together. This imagemoves us beyond predictions to something we can see andmeasure.”

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treadmill. The researchers attached sensors to shoelaceknots as co-author Christine Gregg, a runner, walked andran on a treadmill. There are two common types of knotused to tie shoelaces, known as the ‘granny knot’ and the‘square knot’ of which the latter is stronger. Ms Greg tiedher shoes with the weaker granny knot so that theresearchers could have a better chance of watching itunravel. The researchers also repeatedly swung a pendulumarm with a shoelace knot tied on it to better analyse forcesthe knots experienced. Using slow-motion video, the teamuncovered two stages of knot slippage: a gradual looseningwith each step, and a sudden ‘catastrophic failure’. Whenthe knot started to unravel, it fell apart within two strides.

Representation of hypothesised stages of knot failure. Repeated impactcauses the centre of the knot to incrementally loosen which reducesfrictional effects and magnifies the effects of the inertial imbalancebetween the free ends and loops. Additionally, the impact of stompingcauses slight pull through of the free end, which increases the inertialeffects of the free end, enabling further free-end pull through. Eventually,the inertial effect of the free end is sufficiently large that the knot failssuddenly and catastrophically. (Credit: Daily-Diamond CA, Gregg CE,O’Reilly OM., Proc. R. Soc. A, 2017)

The researchers were surprised by the g-force the knotexperienced as it bobbed up and down, which was morethan seven times the force of gravity. They said that theimpact makes the knot in the shoe stretch and then relaxwhile the action of swinging the leg pulls on the ends ofthe laces. The researchers found these forces could lead tothe failure of a knot in just a few strides. They discoveredthat the dynamic forces acting upon laces while jogging orwalking are a bit like an ‘invisible hand’ undoing the knot.

Of course, not all knots come off in a few strides.The researchers found that different knot-tying techniques,types of laces and levels of knot tightness all factor intohow long it takes shoelaces to come undone. A really tightdouble knot can usually get an athlete through a run, forexample. Nevertheless, scientists have at last unravelled a

knotty problem: the forces behind the accidental untyingof shoelaces. For the first time, researchers havedocumented the mechanics of shoelace knots in motion, tounderstand what makes them loosen and ultimately fallapart.

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June 2017, Vol. 19 No. 9

Believe It or Not – A Cat is the ‘Discovererin Serendipity’ of the First Plastic

Confused at the caption ? Please do not be – the issueis not that complex. Science, the search for

knowledge, is an endless pursuit. Newer scientificdiscoveries continue to be made – some are the outcomeof sustained efforts and some are made in serendipity. Butthe credit definitely goes to the discoverers, althoughsometimes with controversy. But who has even dreamt thatthe credit of a scientific discovery should go to a scientist’spet? However incredible, the story goes like that.

It is about the discovery of ‘milk plastic’ at the endof the 19th century by a Bavarian (Germany) chemist, AdolfSpitteler. The credit of the discovery should indeed go tohis pet cat. As the story goes, one night the cat knockedover a bottle of formaldehyde in Spitteler’s laboratory, andthe formaldehyde dripped into the dish of milk kept forthe cat. Unaware of the consequences, the hapless cat drankthat polluted milk and died. But most interestingly, Spittelerdiscovered in the next morning that the milk had beencurdled by formaldehyde into a new plastic – a solid, horn-like material. The material was actually casein, a family ofmilk proteins that impart to milk its white colour. The namecasein stems from the Latin word ‘caseus’ for cheese.Spitteler started his research and development work on thisnew plastic.

At around the same time, a German printer, WilhelmKrische, started searching for wipe-clean alternatives to theslate tablets used by schoolchildren because paper was tooexpensive to be wasted on kids at that period of time. Oncetheir method of preparing milk plastic was perfected,Krische and Spitteler filed a patent for their new milk-based material in 1899 and set up the first company tomake casein plastic on an industrial scale.

As expected, the chemistry behind the production ofthis plastic was joining together smaller monomer subunits,

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i.e. individual casein protein molecules into longerpolymeric chains. First, the milk is skimmed to removefat, then treated with either acid or an enzyme (rennet),which causes casein protein monomers to polymerise andprecipitate into a solid mass. The latter is separated,washed, dried and treated with alkali, which turns caseinchunks into water-soluble caseinates in the shape of adough-like paste that can be cut and curved into rods orsheets using heat and pressure. To prevent the plastic frombeing soluble in water, it is ‘cured’ in formaldehyde solutionfor up to a year.

Casein plastic enjoyed its heydays in the 1920s andthe ‘30s since a variety of materials like buttons, buckles,knitting needles, jewellery, pens, pots and much more couldbe made from it. Buttons were particularly popular sincethey could withstand the heat of an iron much better thanother materials around at the time could. Moreover, thisplastic could be easily dyed into a rainbow of differentcolours, including exotic tortoiseshell or horn-effect

patterns. Some of the many different brand names forcasein-based plastics are Lactoid, Aladdinite and Galalith(‘milk stone’ in Greek). A fashion designer from Hanover,Germany (casein’s spiritual home) has even develped a silkycasein-based fabric, known as QMilch, from powderedmilk. After the second World War, the advent of easy-to-make polymers like polyester resins has virtually replacedcasein-based plastic materials, buttons in particular, fromthe market. However, it is still used in glues and coatings,particularly for paper and card, and also has more artyapplications in paints and photography emulsions.

The non-edible uses of casein as a fixative in paintsused for creating murals, and also in glue date back to theancient Egyptians. But its use in solid plastics made itsbeginning at the expense of the life of Spitteler’s cat – anact in serendipity.

Professor Manas Chakrabarty, FRSCFormerly, Department of Chemistry

Bose Institute, Kolkata