We Know You’re Humming The Theme Song…

here’s a happy cell to welcome summer :)

So many ways to transport…and these are just a few!

Damage From Wayward Weedkiller Keeps Growing

Two weeks ago, in a remarkable move, the State Plant Board of Arkansas voted to ban the sale and use of a weedkiller called dicamba. It took that action after a wave of complaints about dicamba drifting into neighboring fields and damaging other crops, especially soybeans.

That ban is still waiting to go into force. It requires approval from a committee of the state legislature, which will meet on Friday.

Estimates of dicamba’s damage, however, continue to increase. Since the Plant Board’s vote, the number of dicamba-related complaints in Arkansas has soared to 550. Reports of damage also are increasing in the neighboring states of Tennessee, Missouri and Mississippi. The total area of damaged soybean fields could reach 2 million acres.

“I’ve never seen anything even close to this,” says Larry Steckel, a weed specialist at the University of Tennessee. “We have drift issues every year in a handful of fields, but I’ve never seen anything like this.”

Dicamba is not a new weedkiller; it’s been around for 50 years. It’s being used in a new way, though, because the biotech company Monsanto is now selling new soybean and cotton varieties that have been genetically altered to tolerate dicamba.

A sprayer covers a soybean field with an herbicide to control weeds. Scott Sinklier/Getty Images

ProtoPhotosynthesis™

Penicillin

Penicillin is a widely used antibiotic prescribed to treat staphylococci and streptococci bacterial infections. 

beta-lactam family 

Gram-positive bacteria = thick cell walls containing high levels of peptidoglycan

gram-negative bacteria = thinner cell walls with low levels of peptidoglycan and surrounded by a lipopolysaccharide (LPS) layer that prevents antibiotic entry 

penicillin is most effective against gram-positive bacteria where DD-transpeptidase activity is highest.

Examples of penicillins include:

amoxicillin

ampicillin

bacampicillin

oxacillin

penicillin

Mechanism(s)

Penicillin inhibits the bacterial enzyme transpeptidase, responsible for catalysing the final peptidoglycan crosslinking stage of bacterial cell wall synthesis.

Cells wall is weakened and cells swell as water enters and then burst (lysis)

Becomes permanently covalently bonded to the enzymes’s active site (irreversible)

Alternative theory: penicillin mimics D-Ala D-Ala

Or may act as an umbrella inhibitor

Resistance

production of beta-lactamase - destroys the beta-lactam ring of penicillin and makes it ineffective (eg Staphylococcus aureus - most are now resistant)

In response, synthetic penicillin that is resistant to beta-lactamase is in use including egdicloxacillin, oxacillin, nafcillin, and methicillin. 

Some is resistant to methicillin - methicillin-resistant Staphylococcus aureus (MRSA).  

Demonstrating blanket resistance to all beta-lactam antibiotics -extremely serious health risk.

With all the biochemistry jokes being thrown around, here’s one from my end of the biology spectrum!

Confused about what is meant by 5’ to 3’ and 3’ to 5’ in DNA? We have a GIF for that!