Tag: rivers

oxazepam and fish behavior

Oxazepam

Chemical structure of oxazepam

Traces of drugs are floating around rivers and streams all across the country. They are introduced to the ecosystem when we take medication, metabolize them and flush them down the toilet. Because they are present in low amounts in the environment they have not been thought to be of huge concern to the species that inhabit waterways. But, a new study shows that traces of oxazepam, a benzodiazepine and antianxiety medication, can alter behavior in wild Euorpean perch, making them more active than normal. From The New York Times:

Researchers then took baby fish hatched from the roe of wild perch in what they considered a drug-free waterway, and divided them into three groups of 25. One group had no exposure to Oxazepam; the other two were placed in water with what researchers called a low concentration, at three times higher than the Fyris River, or an extremely high concentration, at 1,500 times higher.

The more Oxazepam they ingested the more active the fish were, measured by the number of swimming motions in a 10-minute period. They were also less social, spending less time near a section of the tank with other fish and more time near an empty compartment. And they were quicker to grab and eat zooplankton. At the highest Oxazepam concentration, fish were also bolder, measured by how long it took them to leave a box in the tank and explore new territory.

“Basically, no one left the box before they were subjected to the drug,” said Dr. Brodin, who said he saw the difference when he entered the room each day. The non-exposed fish “were hiding basically,” while the others “were out there, greeting me. They were totally different fish.”

It should be noted that the lowest concentration that the researchers measured is above the concentration usually observed in waterways. Fish in real world conditions may not have any altered behavior at all.

resistant bacteria from labs enter rivers in china

bacteria

In China, resistant bacteria from molecular biology experiments are turning up in rivers and streams. Molecular biologists use different resistant strains in order to clone bacteria and produce different proteins. In the US, academic and industrial labs have implemented steps to prevent these resistant genes from being introduced into our environment. China, it appears, still has a ways to go before they get a handle on this. From C&EN:

But because this technique is still commonly used in molecular biology labs, some researchers have been concerned that these experiments could release resistance genes into the environment. To search for antibiotic-resistance genes introduced by synthetic plasmids, Jun-Wen Li at the Institute of Health and Environmental Medicine, in Tianjin, China, and his colleagues took water samples from six Chinese rivers downstream of densely populated cities. They extracted plasmids from the samples and transferred the DNA into Escherichia coli. Then they screened the bacteria for a gene commonly used in academic and industrial labs that confers resistance to the antibiotic ampicillin. To determine if a gene in a sample came from a manmade source, they used polymerase chain reaction to look for sequences unique to several synthetic plasmids.

The researchers found synthetic resistance genes in all six rivers. Of all of the ampicillin-resistance plasmids they found in the rivers, about 27% had the synthetic vector-sourced gene.

More here.

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