Nerdy Science Blog

When did human start eating fish?  Why did human eat fish?  As a creature being on the land, it is unlikely for early human to think fish as a source of food.

An international team of research conducted a chemical analysis of protein collagen of a 40,000-year-old bone found at Tianyuan Cave near Beijing.  They examined the ratios of isotopes of nitrogen and sulfur, and determined that the bone owner was a regular fish consumer.  This study became direct evidence that the earliest modern human who ate fish was back in 40,000 years ago.

This regular fish consumption evidence was before the effective making of fishing equipment.  It is believed that the consumption of aquatic resources may be a reflection of pressure from expanding population when modern human emerged across Eurasia.

The study is published in Proceedings of the National Academy of Sciences.

The set of genes that involve in development of teeth has been identified by researchers at Georgia Tech, University of Tennessee, and University of Georgia.  The finding was published on February issue of PLos Biology.

Extinct eel-like fish conodonts had no teeth in their mouth but in the throat (pharnyx), and one of the researchers, Darrin Hulsey first identified the correlation between the number of teeth in oral jaw and throat in fish.  So the researchers used the rapidly evolving cichlids of Africa’s Lake Malawi to study their dentition development.  Researchers had successfully identified the common gene regulatory circuit of the fish, which was the same as the jawless fish.

These fish had the same incisors and molars as modern vertebrate like human.  The finding of the core genes did not only helped to identify the genes that control the teeth development in human, but might also help to map the development of hair or feather.

The authors in this finding were Gareth Fraser, Darrin Husley, Ryan Bloomquist, Kristine Uyesugi, Nancy Manley and Todd Streelman.

(news [journal])

Saprolegnia is a fungus that is a normal component of freshwater aquarium environments. It feeds on dead and decaying matter helping to rid the aquarium of waste. When an aquarium is properly maintained, Saprolegnia is harmless to healthy fish. However, when the water of an aquarium becomes overly littered with decaying matter, or when fish become sick or develop wounds, Saprolegnia can harm fish.

Saprolegnia spores are present in most all freshwater aquariums. The spores are not visible and will circulate silently until a suitable substrate is present for its attachment. Saprolegnia spores target dead fish that have not been removed from the tank, uneaten fish food, infertile fish eggs, and wounds that may be present on live fish. Saprolegnia presents as white to gray patches on the skin of fish that become more hair-like, and cottony as the disease progresses. If left untreated, Saprolegnia can erode into deeper tissues of the fish and disrupt internal body fluids leading to death of the fish.

Treatment of Saprolegnia in aquarium fish involves removing infected fish from the tank, placing them in a separate tank or bowl, and adding an agent to the water of this tank to disrupt the growth process of the fungus. Success of treatment depends on the extent of the body of the fish that is covered with the fungus. Some agents that can be added to the treatment tank include, salt, malachite green, potassium permanganate, methylene blue, antifungal medications, and copper. Each agent should be used under certain conditions and directions should be followed carefully to avoid causing further damage to infected fish.

Though there are many treatments that can be effective when Saprolegnia attacks aquarium fish, preventative measures are easy and necessary to ensure aquarium fish remain free of Saprolegnia infections. Preventing Saprolegnia outbreaks in an aquarium begins by maintaining healthy water. Fostering healthy aquarium water includes, small and frequent water changes, removing dead fish, vacuuming excessive decaying food, keeping the pH of the water in certain parameters, maintaining minerals, such as calcium at proper levels, preventing the buildup of ammonia and nitrites in the tank, not overfeeding fish, and adding live plants to the aquarium.

Water change is essential in removing waste products, nitrates, phosphates, ammonia and nitrites and also for replacing trace elements in the tank. Monitoring the levels of ammonia, nitrites, and pH of the water is also very important. High levels of ammonia and extremes of pH can cause burns to fish resulting in wounds to which Saprolegnia can attach and proliferate. High nitrite levels are toxic to fish and should also be monitored.

In addition to maintaining clean, healthy water, monitoring fish for wounds that may be caused by attacks from aggressive fish, sharp surfaces in the tank, or from rough netting and fish handling technique is helpful in prevention. Removing these hazards and handling fish carefully can help prevent wounds that become surfaces for Saprolegnia attachment and infection.

Saprolegnia is a normal part of clean, healthy, freshwater aquariums. Healthy fish are generally safe from infection by Saprolegnia. Clean water, vigilant monitoring, and removal of waste products from the aquarium will promote healthy fish. Prevention is the easiest method for controlling Saprolegnia outbreaks. However, when prevention fails, there are treatments available that can be effective in curing infected fish.

[pic][pic][pic][pic][pic]

Mercury contamination in fish has been a serious problem that can harm human’s health.

A quick and simple method to detect mercury in fish has been developed by researchers at the University of Pittsburgh.  The method will use fluorescent substance to contact with fish, and if there is any presence of oxidized mercury, the substance will glows in bright green colour.  This does not only give qualitative result (like the traditional test kits do), but also quantitative result.  This technique is developed in the laboratory of Kazunori Koide.  The new technique can be applied onsite.  It only takes 10 to 30 minutes to detect mercury level in fish.

The fluorescence detection method can also be used in detecting mercury in wastewater.

(news [pic])

Oral vaccine is not a new concept in the field of vaccination.  However professor Yang Huey-lang’s research team at National Cheng Kung University developed oral vaccines for fish.  This achievement have won them the “2008 Crazy Idea” contest, which is a biotechnology competition organized by Taiwan’s Industrial Development Bureau.  Patents have been granted in Taiwan and the US for the vaccines which are developed with gene-engineering techniques.  Vaccines are transformed into carrier bacteria and the bacteria are fed to plankton.  The planktons that contain vaccine will be fed to fish to induce immunological response to pathogens.  The development of the vaccines took the team three years and 60,000 cobias were tested.  The chance of surviving after oral vaccination is increased from 40% to 80%.  The oral vaccination is easier and more convenient in term of cost and time compared to conventional vaccines injection.

(news)

This fish won’t turn into delicious sashimi on your table unless you are Bender from Futurama.  This robotic sea bream is named ‘Tai-robot-kun’ and approximately 7 kg.  It is developed by Professor Ikuo Yamamoto, University of Kitakyushu as an underwater survey robot.  I wonder if the Japanese will develope a robotic whale or not.

(news [via])

Here I present you three posts that brighten my day.

1. Zooillogix: Future Fish Will “Catch Themselves” – “Scientists at the Marine Biological Laboratory (MBL) at Wood’s Hole are attempting to train fish to do the stupidest thing possible, catch themselves in nets when beckoned by fishermen.”
2. Advocate: Labor of Love [via Truemors] – “Wanting to have a biological child is neither a male nor female desire, but a human desire.”
3. CBS News: Medicine’s Cutting Edge: Re-Growing Organs [via Gizmodo] – “That powder is a substance made from pig bladders called extracellular matrix. It is a mix of protein and connective tissue surgeons often use to repair tendons and it holds some of the secrets behind the emerging new science of regenerative medicine.”