#1 Gene for autoimmunity

Rare genetic variants in the protein sialic acid acetylesterase (SASE) are linked to common human autoimmune diseases, including type 1 diabetes, arthritis, and Crohn’s disease. In mice, defects in the protein have been linked to problems in B-cell signaling and the development of auto-antibodies.

I. Surolia, et al., “Functionally defective germline variants of sialic acid acetylesterase in autoimmunity,” Nature, 466:243-7. Epub 2010 Jun 16. Eval by Mark Anderson, UCSF Diabetes Center; Anthony DeFranco, University of California, San Francisco; Takeshi Tsubata, Tokyo Medical University, Japan.

#2 Cell mobility illuminated

Using light to activate a the protein Rac in a single cell, researchers show how the protein can induce a group of epithelial cells to polarize en masse, suggesting that these cells can sense movement as a group.

X. Wang, et al., “Light-mediated activation reveals a key role for Rac in collective guidance of cell movement in vivo,” Nat Cell Biol, 12:591-7. Epub 2010 May 16. Eval by Susan Hopkinson and Jonathan Jones, Northwestern University Medical School; Ekaterina Papusheva and Carl-Phillip Heisenberg, Max-Plank-Institute for Molecular Cell Biology and Genetics; Jonathan Chernoff, Fox Chase Cancer Center.

#3 How the brain communicates

Reproducing the electrical activity of the neurons in the mouse cortex, researchers demonstrate how different layers of the brain communicate to piece together information from a wide range of sensory inputs — a process that many neuroscientists consider a major mystery in the field.

H. Adesnik and M. Scanziani. “Lateral competition for cortical space by layer-specific horizontal circuits,” Nature, 464:1155-60, 2010. Eval by Aguan Wei and Jan-Marino Ramirez, University of Washington; James Cottam and Michael Hausser, University College London.

#4 Backwards-working neurons

Normally neurons respond strongly to synapses located closer to the cell’s center and weakly to those located on the cell’s tips. But the authors found that certain neurons important in spatial memory react more strongly to the distant brain signals than those from nearby neurons.

V. Chevaleyre and SA Siegelbaum. “Strong CA2 pyramidal neuron synapses define a powerful disynaptic cortico-hippocampal loop,” Neuron, 66:560-72, 2010. Eval byStephen M Fitzjohn and Graham Collingridge, MRC centre for Synaptic Plasticity; Johannes Hell, University of California, Davis.

#5 Cell-swallowing proteins

Researchers identify two proteins vital to — and perhaps responsible for initiating — the way eukaryotic cells take up ligands bound to the surface receptors into membrane-bound vesicles, a process essential for a vast number of cellular functions, including nutrient uptake, receptor signaling, pathogen entry, and drug delivery.

WM Henne, et al., ” FCHo proteins are nucleators of clathrin-mediated endocytosis,” Science, 328:1281-4, 2010. Eval by Martin Lowe, University of Manchester; Pekka Lappalainen, Institute of Biotechnology, Finland.

#6 Less genetic “dark matter”

In opposition to the idea that much of the mammalian genome is uselessly transcribed into non-functional RNA molecules, researchers demonstrate that there is relatively little RNA derived from the expanses of DNA in between functional genes.

H van Bakel et al., “Most ‘dark matter’ transcripts are associated with known genes,” PLoS Biol, 2010 May 18;8(5):e1000371. Eval by Daniel Reines, Emory University School of Medicine; Adnane Sellam and Andre Nantel, National Reseasrch Council of Canada.

#7 Death receptor helps cancer live

The apoptosis receptor DC95 that induces cell death may also promote cancer growth, providing a new possible target for cancer therapies.

L. Chen et al., “CD95 promotes tumour growth,” Nature, 465:492-6, 2010. Eval by Sharad Kumar, Centre for Cancer Biology, Austrailia; Astar Winoto, University of California, Berkeley.

The F1000 Top 7 is a snapshot of the highest ranked articles from a 30-day period on Faculty of 1000 Biochemistry, as calculated on July 8, 2010. Faculty Members evaluate and rate the most important papers in their field. To see the latest rankings, search the database, and read daily evaluations, visit http://f1000.com.

Jennifer Welsh contributed to this article.

www.technofender.com

Synthetic Biology is an emerging field. Much work still is to be done, but the progress already made points out to an exciting sci pathway.

Whether the applications of the Synth-Bio are conducted towards the production of new pharmaceutical products, or to the manufacturing of specialized biocomponents – that might help to reduce the contamination – it really, really has possibilities.

In a  research conducted by Dr. Pamela Silver at the Harvard Medical School (HMS) a  milestone was reached.

As every engineer knows, the design must be strongly tested before going on to the manufacturing issues. That makes it very close to the Maths models. In fact, if a new structure is to be built, an engineer would test the design FIRST, against some complex mathematical models that would output the resistance to pressure, tangential effort and aome other physical factors. After that, the process of building – let’s say a bridge – would include some considerations.

Silver et al, achieved successfully at inducing a memory loop in yeast cells and producing a new mathematical model that predicted – with a certain degree of accuracy – the behaviour of the cells.

The experiment was about including a pair of genes – synthetic – with the ability to produce transcription factors.

Transcription Factors are capable of regulating the activity of specific genes, forcing them to synthetize (or otherwise disable) a specific protein.

The first gene reacted to the presence of Galactose, producing a transcription factor, which in turn, activated the second gene. Then, the second gene reacted by producing a transcription factor, which at the end reactivated itself (the second gene). This caused a feedback loop, that was maintained by the presence of Galactose.

But, when the Galactose was extracted from the medium, then the first gene stopped producing its transcription factor, but the second gene continued producing its own.

The new cells – as expected – kept producing the second gene transcription factor and the experiment was successful.

“Essentially what happened is that the cell remembered that it had been
exposed to galactose, and continued to pass this memory on to its descendents,” says Ajo-Franklin, a co-worker of Dr. Silver. “So after many cell divisions, the feedback loop remained intact without galactose or any other sort of molecular trigger.”

Most important is that the construction phase was guided by the mathematical model. That has profound implications in the future of the Synthetic Biology.

If “black boxes” are to be constructed then it’s positively compulsory to be backed-up on the Mathematical models. Accuracy is needed as to foresee a future when black boxes would be plugged into living cells, knowing exactly what the results will be. The same way a Computer Technician plugs a memory chip into the appropriate mainboard slot of the PC.

http://www.technofender.com/blog/biotechnology/synthetic-biology-inducing-memory-in-yeast-cells/

Structure of DNA

Legend:
Illustration of the double helical structure of the DNA molecule.

The structure of DNA is illustrated by a right handed double helix, with about 10 nucleotide pairs per helical turn. Each spiral strand, composed of a sugar phosphate backbone and attached bases, is connected to a complementary strand by hydrogen bonding (non- covalent) between paired bases, adenine (A) with thymine (T) and guanine (G) with cytosine (C).

Adenine and thymine are connected by two hydrogen bonds (non-covalent) while guanine and cytosine are connected by three.

This structure was first described by James Watson and Francis Crick in 1953.

Protein Synthesis

 

Legend:
Process whereby DNA encodes for the production of amino acids and proteins.

This process can be divided into two parts:

1. Transcription
Before the synthesis of a protein begins, the corresponding RNA molecule is produced by RNA transcription. One strand of the DNA double helix is used as a template by the RNA polymerase to synthesize a messenger RNA (mRNA). This mRNA migrates from the nucleus to the cytoplasm. During this step, mRNA goes through different types of maturation including one called splicing when the non-coding sequences are eliminated. The coding mRNA sequence can be described as a unit of three nucleotides called a codon.

2. Translation
The ribosome binds to the mRNA at the start codon (AUG) that is recognized only by the initiator tRNA. The ribosome proceeds to the elongation phase of protein synthesis. During this stage, complexes, composed of an amino acid linked to tRNA, sequentially bind to the appropriate codon in mRNA by forming complementary base pairs with the tRNA anticodon. The ribosome moves from codon to codon along the mRNA. Amino acids are added one by one, translated into polypeptidic sequences dictated by DNA and represented by mRNA. At the end, a release factor binds to the stop codon, terminating translation and releasing the complete polypeptide from the ribosome.

One specific amino acid can correspond to more than one codon. The genetic code is said to be degenerate.

Simplified Diagram of Cellular Metabolism

The three stages of cellular metabolism lead from food to waste products in animal cells. This series of reactions produces ATP, which is then used to drive biosynthetic reactions and other energy-requiring processes in the cell. Stage 1 mostly occurs outside cells––although special organelles called lysosomes can digest large molecules in the cell interior. Stage 2 occurs mainly in the cytosol, except for the final step of conversion of pyruvate to acetyl groups on acetyl CoA, which occurs in mitochondria. Stage 3 occurs in mitochondria.  

Biotechnology: Present and Future

Legend:

Areas of applied biotechnology:

In 1885, a scientist named Roux demonstrated embryonic chick cells could be kept alive outside an animal’s body. For the next hundred years, advances in cell tissue culture have provided fascinating glimpses into many different areas such as biological clocks and cancer therapy.

Monoclonal antibodies are new tools to detect and localize specific biological molecules. In principle, monoclonal antibodies can be made against any macromolecule and used to locate, purify or even potentially destroy a molecule as for example with anticancer drugs.

Molecular biology is useful in many fields. DNA technology is utilized in solving crimes. It also allows searchers to produce banks of DNA, RNA and proteins, while mapping the human genome. Tracers are used to synthesize specific DNA or RNA probes, essential to localizing sequences involved in genetic disorders.

With genetic engineering, new proteins are synthesized. They can be introduced into plants or animal genomes, producing a new type of disease resistant plants, capable of living in inhospitable environments (i.e. temperature and water extremes,…). When introduced into bacteria, these proteins have also produced new antibiotics and useful drugs.

Techniques of cloning generate  large quantities of pure human proteins, which are used to treat diseases like diabetes. In the future, a resource bank for rare human proteins or other molecules is a possibility. For instance, DNA sequences which are modified to correct a mutation, to increase the production of a specific protein or to produce a new type of protein can be stored . This technique will be probably play a key role in gene therapy.

The-Scientist.com, July 28, 2010, by Megan Scudellari

#1 Neurons complete hippocampus loop

There’s a new, important function for a once-obscure cell population in the brain: CA2 pyramidal neurons, a subset of cells in the hippocampus, form a link between electrical inputs and outputs in the hippocampus.

V. Chevaleye et al., “Strong CA2 pyramidal neuron synapses define a powerful disynaptic cortico-hippocampal loop,” Neuron, 66:560-72, 2010. Eval by Stephen Fitzjohn and Graham Collingridge, MRC Centre for Synaptic Plasticity, UK; Johannes Hell, University of California, Davis.

#2 Non-overlapping neurons

The medial entorhinal cortex, a hub for memory and navigation in the brain, consists of two tangled but functionally separate networks that have different long-range axonal targets, and thus may be involved in different functions in the brain. The finding offers insights to how neural networks function, and — in conditions like epilepsy — dysfunction.

C. Varga et al., “Target-selective GABAergic control of entorhinal cortex output,” Nat Neurosci, 13:822-4, 2010. Eval by Edvard Moser, Norwegian University of Science and Technology, Norway; Jeff Isaacson, University of California, San Diego.

#3 “We’re going to need a bigger model”

In a detailed mathematical analysis, researchers analyze the capacity of computational models to model neuronal oscillations — the repetitive rise and fall of membrane potentials. They find that current single-cell oscillation models are not adequate, and there is a need for additional computational models to assess this mechanism.

M.W. Remme et al., “Democracy-independence trade-off in oscillating dendrites and its implications for grid cells,” Neuron, 66:560-72, 2010. Eval by Lisa Giocomo and Edvard Moser, Norwegian University of Science and Technology, Norway; Neil Burgess, University College London.

#4 Key step to making dendrites

For the first time, researchers demonstrate that a protein that fuses membranes instructs the development of dendrites in C. elegans. The protein, EFF-1, causes overlapping branches to fuse together, a novel control mechanism for the poorly understood morphogenesis of dendrites.

M. Oren-Suissa et al., “The fusogen EFF-1 controls sculpting of mechanosensory dendrites,” Science, 328:1285-8, 2010. Eval by Tina Schwabe and Thomas Clandinin, Stanford University, California; Andrew Chisholm, University of California, San Diego.

#5 How amyloid kills synapses

New findings suggest an explanation for why amyloid causes synapses to fail in Alzheimer’s and other diseases: The binding of amyloid beta oligomers causes glutamate receptors in synaptic membranes to form clusters, resulting in increased intracellular calcium and eventual deterioration of the synapse.

M. Renner et al., “Deleterious effects of amyloid beta oligomers acting as an extracellular scaffold for mGluR5,” Neuron, 66:739-54, 2010. Eval by Joel Bockaert, Institute of Functional Genomics, France; Hui-Chen Lu and Kenneth Mackie, Indiana University.

#6 New mechanism for synaptic plasticity

Researchers have uncovered another key mechanism behind one of the most important processes in learning and memory, synaptic plasticity. Specifically, two signaling molecules, BRAG2 and Arf6, trigger endocytosis of AMPA receptors in the brain, inducing long-term depression (LTD), a long-lasting reduction in the sensitivity of neurons and a well-known form of synaptic plasticity.

R. Scholz et al., “AMPA receptor signaling through BRAG2 and Arf6 critical for long-term synaptic depression,” Neuron, 66:768-80, 2010. Eval by Stephen Fitzjohn and Graham Collingridge, MRC Centre for Synaptic Plasticity, UK; Johannes Hell, University of California, Davis.

#7 Cell division affects cell fate

Through live imaging of a zebrafish embryo, researchers show that asymmetrical cell division is important in establishing cell fate in the vertebrate central nervous system.

P. Alexandre et al., “Neurons derive from the more apical daughter in asymmetric divisions in the zebrafish neural tube,” Nat Neurosci, 13:673-9, 2010. Eval by Judith Eisen, University of Oregon; Caren Norden and William Harris, University of Cambridge, UK.

The F1000 Top 7 is a snapshot of the highest ranked articles from a 30-day period on Faculty of 1000 Neuroscience, as calculated on July 22, 2010. Faculty Members evaluate and rate the most important papers in their field. To see the latest rankings, search the database, and read daily evaluations, visit http://f1000.com.

UCLA, July 28, 2010  —  The ability to tell time is fundamental to how humans interact with each other and the world. Timing plays an important role, for example, in our ability to recognize speech patterns and to create music.

Patterns are an essential part of timing. The human brain easily learns patterns, allowing us to recognize familiar patterns of shapes, like faces, and timed patterns, like the rhythm of a song. But exactly how the brain keeps time and learns patterns remains a mystery.

In this three-year study, UCLA scientists attempted to unravel the mystery by testing whether networks of brain cells kept alive in culture could be “trained” to keep time. The team stimulated the cells with simple patterns — two stimuli separated by different intervals lasting from a twentieth of a second up to half a second.

After two hours of training, the team observed a measurable change in the cellular networks’ response to a single input. In the networks trained with a short interval, the network’s activity lasted for a short period of time. Conversely, in the networks trained with a long interval, network activity lasted for a longer amount of time.

The UCLA findings are the first to suggest that networks of brain cells in a petri dish can learn to generate simple timed intervals. The research sheds light on how the brain tells time and will enhance scientists’ understanding of how the brain works.

The study was supported by a grant from the National Institute of Mental Health.

 Source & Journal:      Hope A Johnson, Anubhuthi Goel, Dean V Buonomano. Neural dynamics of in vitro cortical networks reflects experienced temporal patterns. Nature Neuroscience, 2010; DOI: 10.1038/nn.2579

University of California – Los Angeles (2010, July 19). Cultured brain cells taught to keep time.

FORBES.COM, July 28, 2010, by Seth Borenstein

 

 

WASHINGTON — Despite their tiny size, plant plankton found in the world’s oceans are crucial to much of life on Earth. They are the foundation of the bountiful marine food web, produce half the world’s oxygen and suck up harmful carbon dioxide.

And they are declining sharply.

Worldwide phytoplankton levels are down 40 percent since the 1950s, according to a study published Wednesday in the journal Nature. The likely cause is global warming, which makes it hard for the plant plankton to get vital nutrients, researchers say.

The numbers are both staggering and disturbing, say the Canadian scientists who did the study and a top U.S. government scientist.

“It’s concerning because phytoplankton is the basic currency for everything going on in the ocean,” said Dalhousie University biology professor Boris Worm, a study co-author. “It’s almost like a recession … that has been going on for decades.”

Half a million datapoints dating to 1899 show that plant plankton levels in nearly all of the world’s oceans started to drop in the 1950s. The biggest changes are in the Arctic, southern and equatorial Atlantic and equatorial Pacific oceans. Only the Indian Ocean is not showing a decline. The study’s authors said it’s too early to say that plant plankton is on the verge of vanishing.

Virginia Burkett, the chief climate change scientist for U.S. Geological Survey, said the plankton numbers are worrisome and show problems that can’t be seen just by watching bigger more charismatic species like dolphins or whales.

“These tiny species are indicating that large-scale changes in the ocean are affecting the primary productivity of the planet,” said Burkett, who wasn’t involved in the study.

When plant plankton plummet – like they do during El Nino climate cycles_ sea birds and marine mammals starve and die in huge numbers, experts said.

“Phytoplankton ultimately affects all of us in our daily lives,” said lead author Daniel Boyce, also of Dalhousie University in Halifax, Nova Scotia. “Much of the oxygen in our atmosphere today was produced by phytoplankton or phytoplankton precursors over the past 2 billion years.”

Plant plankton – some of it visible, some microscopic – help keep Earth cool. They take carbon dioxide – the key greenhouse gas – out of the air to keep the world from getting even warmer, Boyce said.

Worm said when the surface of the ocean gets warmer, the warm water at the top doesn’t mix as easily with the cooler water below. That makes it tougher for the plant plankton which are light and often live near the ocean surface to get nutrients in deeper, cooler water. It also matches other global warming trends, with the biggest effects at the poles and around the equator.

Previous plankton research has mostly relied on satellite data that only goes back to 1978. But Worm and colleagues used a low-tech technology – disks devised by Vatican scientist Pietro Angelo Secchi, in the 19th century. These disks measure the murkiness of the ocean. The murkier the waters, the more plankton.

It’s a proxy the scientific community has long accepted as legitimate, said Paul Falkowski of Rutgers University, who has used Secchi disk data for his work.

He and other independent scientists said the methods and conclusions of the new study made sense.

One of the world’s richest fisheries is off the coast of Peru. In most years winds from the southeast push warm surface water away from the coast. In its place, upwelling brings to the surface cold water rich in nutrients. These provide nourishment for the microscopic plants know as plankton .

Plankton normally provide food for a vast community of anchovies and other fish.The fish in turn supply food for seabirds. Not only is the fish catch economically important, but the harvesting of bird excrement (guano) provides a supply of valuable fertilizer.

Every few years the pattern of air circulation of the equatorial Pacific changes in a way that affects oceanic upwelling. This weather condition is known as El Niño. During El Nino, upwelling brings up warm water with few nutrients. A serious economic consequences of El Niño is its devastating effect on the Peruvian anchoveta fisheries. Populations of fish and seabirds vanish and anchovy catches dwindle during El Niño. (See our El Niño page.)

Some biologists fear that the over fishing of the anchoveta by humans, plus the eating of anchovies by large fish and seabirds, combined with the injurious effects of an intense El Niño episode, like the one in 1997-98, could reduce the anchoveta stock to such critically low numbers that recovery could be difficult. The 1972-73 El Niño caused a serious drop in the fish catch which took years to recover. Since then, the Peruvian government has worked hard to regulate fishing in their territorial waters. Fortunately they have been succesfull, and the fishery has recovered from even severe El Niños like the one in 1988-1989.

To make it safer for older people, the city added four seconds to the time pedestrians are given to cross intersections like Broadway and 72nd Street.

The New York Times, July 28, 2010, by Anemona Hartocollis  —  New York City has given pedestrians more time to cross at more than 400 intersections in an effort to make streets safer for older residents. The city has sent yellow school buses, filled not with children but with elderly people, on dozens of grocery store runs over the past seven months.

Ana Andujar, 84, second from left, and others attended a meeting in East Harlem on how to make the city more age-friendly.

Emily Berl for The New York Times

The city has allowed artists to use space and supplies in 10 senior centers in exchange for giving art lessons. And it is about to create two aging-improvement districts, parts of the city that will become safer and more accessible for older residents.

Happy resident in a NYC Senior Center

People live in New York because it is like no place else — pulsating with life, energy and a wealth of choices — but there is some recognition among city planners that it could be a kinder and gentler place in which to grow old.

The city’s efforts, gaining strength as the baby boomer generation starts reaching retirement age, are born of good intentions as well as an economic strategy.

“New York has become a safer city, and we have such richness of parks and culture that we’re becoming a senior retirement destination,” said Linda I. Gibbs, New York’s deputy mayor for health and human services. “They come not only with their minds and their bodies; they come with their pocketbooks.”

Retired Couple Biking in Central Park, NYC

The round trip back to cities among empty nesters, rejoining those who simply grow old where they were once young, goes on, of course, across the country, and New York is not the only place trying to ease that passage. Cities like Cleveland and Portland, Ore., have taken steps to become more “age-friendly.” But perhaps never has a city as fast-paced and youth-oriented as New York taken on the challenge.

The Department of City Planning predicts that in 20 years, New York’s shares of schoolchildren and older people will be about the same, 15 percent each, a sharp change from 1950, when schoolchildren outnumbered older residents by more than 2 to 1. By 2030, the number of New Yorkers age 65 and over — a result of the baby boomers, diminished fertility and increasing longevity — is expected to reach 1.35 million, up 44 percent from 2000.

Their economic power is significant. About a third of the nation’s population is over 50, and they control half of the country’s discretionary spending, according to a recent report by AARP, a group representing the interests of retirees. In some ways, the city has tackled the toughest challenges of making itself attractive to its older residents and those across the country who might consider retiring to the Upper East Side or Brooklyn Heights.

Crime has been in decline for close to two decades; the city has added more parkland than at any similar period in its history; and the 311 system has made dealing with the bureaucracy of government agencies and social services more manageable.

Now, the city is looking to enhance life here in more modest, but meaningful, ways. The New York Academy of Medicine adopted the idea of creating an age-friendly city from the World Health Organization in 2007, and went to the City Council and the Bloomberg administration for financial and political support. The academy has held more than 30 town hall meetings and focus groups with thousands of older people across the city. This summer, it is holding more intimate focus groups in East Harlem and on the Upper West Side.

What people say they want most of all is to live in a neighborly place where it is safe to cross the street and where the corner drugstore will give them a drink of water and let them use the bathroom. They ask for personal shoppers at Fairway to help them find the good deals on groceries. They want better street drainage, because it is hard to jump over puddles with walkers and wheelchairs.

“No bingo played here” could be Ms. Gibbs’s motto. She is the conceptual artist behind the city’s initiative, working with the Academy of Medicine. She is at the tail end of the boomer generation, having turned 51 on Sunday, her silvery bob a rebuke to fears of aging.

“The whole conversation around aging has, in my mind, gone from one which is kind of disease oriented and tragic, end- of-life oriented,” Ms. Gibbs said, to being “much more about the strength and the fidelity and the energy that an older population contributes to our city.”

Retired woman enjoys the flowers in NYC Central Park

One of her ideas is to hold a contest to design a “perch” to put in stores or on sidewalks where tired older residents doing errands could take a break. When boomers talk, she listens.

On Thursday, Dorian Block, a policy associate at the academy, held a focus group at the Carver Houses, a city housing project at 103rd Street and Madison Avenue in East Harlem. Sixteen people showed up. (Some meetings have drawn hundreds.)

They complained about broken elevators and litter, and some confessed to being lonely. They said that more stores should have public bathrooms. Now, said Dolores Marquez, 72, “I go to McDonald’s and then I take a coffee because I have to go to the bathroom.”

The academy plans to incorporate the results of the focus groups into two pilot aging-improvement districts, one in East Harlem and the other on the Upper West Side, somewhat akin to business-improvement districts.

The exact details of how the districts will function are still being worked out, but the goal is to create a public-private partnership that would encourage businesses to voluntarily adopt amenities for the elderly. Examples could include window stickers that identify businesses as age-friendly; extra benches; adequate lighting; menus with large type; and even happy hour for older residents.

Living on a pension, but exercising at a reasonably priced gym

The new districts will be run by the academy, and eventually handed over to community groups and expanded to other neighborhoods, said Ruth Finkelstein, the academy’s vice president for health policy. Some worry that what the Bloomberg administration is proposing is a menu of quick and dirty solutions for older residents while, in a tough economy, traditional services like senior centers and bus routes are being cut back.

“When we’re talking about age-friendly, it should not only be the boomers who have retired from law firms, as opposed to the people who have worked all their lives and are now living in Brownsville,” said David Jones, president of the Community Service Society, which advocates for poor people and immigrants.

Fredda Vladeck, an expert at the United Hospital Fund in “naturally occurring retirement communities,” said she worried that the city would forget the frail older people. Ms. Gibbs said the point was to build on what is already there, and to make life better for everyone.

The city enlisted students at New York University’s Wagner Graduate School of Public Service to develop a walking survey that, if adopted, will rate the city’s age-friendliness by standards like the frequency of cracked sidewalks and hospitals.

Slowing the pace of life is tough in New York, where every red light is viewed as a challenge. But the city is trying. While most adults average four feet per second when crossing the street, older residents manage only three, transportation experts say. So signals have been retimed at intersections like Broadway and 72nd Street, where pedestrians now have 29 seconds to cross, four more than before.

Even senior centers are being redefined as places with artists in residence, like Judy Hugentobler, a sculptor from Staten Island. Ms. Hugentobler is teaching art classes at the Educational Alliance’s Sirovich Senior Center, on East 12th Street, in exchange for being able to use the kilns, clay and glazes in her projects.

“Senior centers are great, but they have a stigma whether you like it or not,” said Councilwoman Gale A. Brewer of the Upper West Side. “It’s just not for everybody. But what is for everybody is a bench. What is for everybody is discounts at the grocery store when you’re over 65.”

New York Transit is Fairly Easy to Navigate