As I see it, the ethical challenge and ultimate responsibility of the scientist is to serve Humanity; the scientifically responsible way, is to do it by means of rigour, truth and sincerity, using the state of the art methodologies. Science that would serve truth as ultimate goal not as a tool - or aim to achieve whatever can be achieved regardless of Homo Sapiens interest is inhuman, therefore immoral, worse that amoral.
(humble excuses for the boldness of the statement)
In what way to aid humanity? Science often, while expanding knowledge, has little direct impact on the physical wellbeing of others. Is all that comes under the appellation of science actually science and how can we really separate bad science from good science? In many ways, it looks the same.
The core values of a scientist,in my opinion, are the investigation of the truth, the benefit of the humankind and the environment, the affability in every opinion and aspect.
The environment - scenario, in my opinion, always is the same in its core , only the form changes. In consequence, the protection of the these values, always in my opinion, can become by outgrowing of this environment, by study and by training in the religion especially in Christianity.
In addition and completion of the previous answer, the Christianity has as levers the liberty, the fraternity and the equality, levers that can generate and develop these scientist's core values.
A relative aid to this issue and aspect is the Alexis Carrel's, a French biologist and physiologist, work "L' homme, cet incnnu".
Core values in scientist imply absolute truthfulness, as far as possible remain value-free approach, compromised with society and sustainable consideration thinking in future generations. Science has a reductionist approach where facts are the goal, however there will always certain amount of interpretation by the scientist , acknowledging this will help to improve the selection of what is considered as evidence in certain moment.
Whenever animals or humans are involved respect for their value and sound ethical approach should be included in the valid consent form.
How to protect: There should be a change regarding scientific production as the measure of academic productivity, many articles may not be published if there wasn't the pressure of publish or perish.
Focus should be given towards cooperation between groups rather than primacy over everyone else.
According to the mentioned from me above I would like to add that the study in science should concern in my opinion the history and the philosophy of every scientific yield.