6 . Human beings are not alone in having invented vaccination, while honeybees got there first and they can run what look like vaccination programmes, which has been confirmed by Gyan Harwood of the University of Illinois, Urbana-Champaign.
Queen bees vaccinate their eggs before they are laid. But the question is how the queen receives her antigen supply, for she lives purely on royal jelly, a substance secreted by nurse bees when they are in the life stage of feeding the young. Dr Harwood wondered if the nurses combined the royal jelly they produced with pieces from pathogens they had consumed while eating something brought in from outside.
To test this idea, they collected about 150 nurse bees and divided them among six queenless mini hives equipped with the young to look after. They fed the nurses on sugar-water, and for three of the hives they added Paenibacillus larvae, a bacterium causing a disease, to sugar-water.
Dr Harwood and Dr Salmela labeled the bacteria with a certain dye, to make them easy to track. And, sure enough, microscope confirmed that Paenibacillus larvae were getting into royal jelly secreted by those bees which had been fed with the sugar-water. Moreover, examination of this royal jelly revealed higher levels of defensive substance, compared with royal jelly from bees that had not been mixed with Paenibacillus larvae. This substance is thought to help bee immune systems fight against bacterial infections.
All told, these findings suggest that nurse bees are indeed, via their royal jelly, passing antigens on to the queen, then into eggs. They also mean, because the young receive royal jelly for the first few days after they hatch, the nurses are giving the young the second antigens. Each young bee is therefore being vaccinated twice.
【小题1】What puzzled Dr Harwood from paragraph 2?| A．What the royal jelly consists of. |
| B．Where nurse bees receive pathogens. |
| C．How the antigen come into the queen bees' bodies. |
| D．Whether honeybees run vaccination earlier than man. |
| A．By dividing bees into different roles. |
| B．By keeping track of the special bacterium. |
| C．By changing the components of royal jelly. |
| D．By observing nurse bees' different behaviors. |
| A．Nurse bees are the key to vaccination for bee group. |
| B．The nurse bees pass the antigen only to the queen. |
| C．Bacteria-used royal jelly has fewer defense substances. |
| D．Two vaccinations are given to young bees by caregivers directly. |
| A．A pet guide. | B．A social website. |
| C．An official document. | D．A medical magazine. |
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