Dreaming of a white Christmas!

Pseudomonas syringae is a rod-shaped bacterium which produces ice nucleation active (INA) proteins on its outer membrane which cause water (in plants) to freeze at fairly high temperatures (-4 to -2°C), resulting in injury.

Since the 1970s, P. syringae has been implicated as an atmospheric "biological ice nucleator", with airborne bacteria serving as cloud condensation nuclei. Recent evidence has suggested the species plays a larger role than previously thought in producing rain and snow.

They have also been found in the cores of hailstones, aiding in bioprecipitation. These INA proteins are also used in making artificial snow. The protein InaZ, acts as a mold for ice crystals.

Alternating water-repelling and water-attracting parts of the protein tug nearby water molecules into an orderly, ice-like arrangement.

This alignment process becomes more prominent as water temperatures drops towards the freezing point. P. syringae can crystallize water at around –2˚ C, several degrees above the temperature at which ice crystals commonly form.

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It was Christmas time again, and the town of Chillburst was teeming with activity. Traders and shopkeepers were stocking up on Christmas goodies. Delicious smells of freshly baked gingerbread, plum cakes and cookies wafted from the bakeries, and all the children had come back home for the holidays.

Yet, something was amiss. At least, that was what eleven year old Billy Turner could gather from his mother’s letter. She was looking forward to having him home for the Christmas holidays, and Billy was dying to finish his exams and go home.

Oh, what fun it would be! Mother had written to him about all the wonderful things happening in the town for Christmas, and Billy was looking forward to being a part of the festivities. The Christmas pantomime, the delicious Christmas dinner being planned, and the decorations on the Christmas tree— Billy imagined all of it in his head, and he spent a lot of his exam time dreaming about the holidays.

Thankfully, he wrote his term exams reasonably well despite the distraction, and prepared to go home. But something was missing in his mother’s description of Christmas back home; what was it? Billy couldn’t quite point it out, but it tugged at him. In the end, he shrugged it off and concentrated on packing his trunk.

Billy got onto the train heading home with his schoolmates, all of whom were expected to get down at stations before him. They had a jolly time discussing what they’d asked Santa for that year.

“I’ve asked for a pretty doll wearing a lovely gown— one that says it’s name when I tilt its head”, said Mary Lou, one of his friends. “I saw it in a store, and mother said I could have it for Christmas.”

“I’ve asked for a toy train set that blows real smoke”, said Joe, jumping up and down in his seat. “One that whistles just like this one!”

“Pooh! This one whistles alright but this is an electric train”, said Julian, a studious and serious boy who always had his nose in books, and had his nose in one as they were talking. “I doubt if Santa will be able to get one like you want, in this age of electric trains.” Everyone laughed.

“What have you asked for, Billy?” asked Julian. Billy turned his head away. He had just one Christmas wish every year: to see his mom and dad back together.

His parents were separated, and Billy wished to celebrate Christmas with his Dad more than anything else in the world. His Dad lived in the same town, but he was cold and distant towards Billy. A scientist by profession, he had no time for his family.

“He must have asked for a dog or a cat”, said Joe. “Or a bird”, said Mary Lou. “Or a frog”, giggled Alice. Billy’s love for animals was well known, and his friends liked to tease him about it. Billy smiled good-naturedly. “What did you ask for Julian?” asked Billy. “Books, as usual”, muttered Julian before burying his nose in his book again.

One by one, all the children got down at their respective stations, wishing each other a Merry Christmas. At last, when Billy’s train stopped at the station of Chillburst, he jumped out in happiness, eager to get back home.

But the moment Billy saw the landscape, he knew what was wrong. There was no snow! It was the third week of December, and Billy knew the previous winters to be extremely cold. Snow usually fell in huge drifts, and the roads and the sidewalks would be covered in snow.

The trees had a lovely ice frosting on them, and the town looked as though it had been covered in thick, heavenly white blanket. But to his shock, he found there wasn’t a single speck of snow around. It wasn’t sunny, and there was a cold wind blowing, but no snow at all. How could Christmas be Christmas without snow?

It looked as though everyone thought the same as him, for nobody was smiling. Everyone went about their work in a quiet, efficient manner, but it was apparent that everyone missed the snow, and things just didn’t feel Christmassy without it.

Billy’s mother was waiting for him. Billy ran into her arms. “Mom, why is there no snow? It looks so strange!”His mother looked tired and worn out, but she still managed a smile. “No idea why, Billy”, she said. “Business is bad too. But we will still manage this Christmas.”

Billy went home with her, looking around at the strange unfamiliar winter sights around him. For a few days, Billy was content to be at home eating cookies and cakes that his mother made, and packing presents for his friends and family.

But he missed all his other winter activities— snowball fights in the neighbourhood, tobogganing, and building snowmen in his backyard. It rained some times, but it didn’t snow. All the townspeople kept hoping that it would snow any day now.

It was almost Christmas Eve, and it was time for Billy to visit his Dad. Every year, around Christmas, Billy went to meet his father, and pleaded with him to come home on Christmas Day. His Dad never turned up, and Billy had got used to it. But he missed his father, and still went to see him.

His mother dropped him at his Dad’s office, which was actually a research lab. Billy walked in to find his father busy with his work as usual. “I forgot you were coming William”, said his father casually, and went about his work, ignoring his presence.

Billy sat tongue-tied, watching his father work. His father hardly spoke to him, unless it was about his work. Deciding that saying something was better than saying nothing at all, Billy asked his father what kind of research he was doing.

His Dad brightened up at once. “We’re working on a bacterium here— it’s called Pseudomonas syringae. It’s a very interesting bacterium, because it can make snow. Can you believe that? It has a protein on its membranes which acts like a mould for nearby water molecules— like your mother uses a cookie cutter for shaping cookies from the dough— and changes them into ice crystals! And this is –”

“Dad!” Billy was excited all of a sudden. “Why don’t you use this bacterium to make snow for our town? Can’t you see how upset everyone is without snow?”

His father’s face darkened. “Science is for serious stuff. Not for such frivolous things so that people can go skiing or sledding.”

Billy was very upset. Here was his father, holding the key to the townspeople’s happiness, but refusing to share it with anyone!

“Dad! You are so selfish! You think only of yourself and your work!” Billy could hold it in no longer. “You don’t care about anyone else’s happiness! You don’t think of Mom.

You don’t even think of my happiness! You never even come home for Christmas though I come and ask you every year!”

Sobbing, Billy ran out. He couldn’t get over his disappointment. His mother tried asking him what was wrong, but he had no answer to give. He cried himself to sleep on Christmas eve, knowing that what he wanted might never happen.

On Christmas morning, Billy didn’t want to get out of bed. It seemed like it had become freezing cold all of a sudden. He felt a hand gently touch his forehead. “Merry Christmas Mom”, he said, without opening his eyes. “Merry Christmas Billy”, said a voice. Billy got up with a start. It wasn’t his mother, it was his Dad!

“Dad! Is this really you?” Billy wondered if he was dreaming. “It’s me alright”, said his Father, smiling. “Open the window and have a look.”

Billy ran to the window. All around was a thick blanket of snow and ice! Had his father done something with the bacteria?

He didn’t know, but his heart was full of happiness. As he went outside to build a snowman with his Dad, while his mother watched them from the kitchen, he thanked Santa for fulfilling his Christmas wish.