Quantitative variables applied to phenological studies of Sargassum vulgare C. Agardh (Phaeophyceae - Fucales) from Ilha Grande Bay, State of Rio de Janeiro

The suitability of quantitative variables for phenological studies was evaluated in a population of the brown seaweed Sargassum vulgare from "Praia das Gordas", Angra dos Reis, Ilha Grande Bay, state of Rio de Janeiro. From June 1998 to May 1999, twenty adult individuals were randomly sampled at bimonthly intervals. Fifteen variables related to the vegetative and reproductive development of perennial and non-perennial parts of the individuals were quantified. Variables related to the non-perennial parts were more useful than those related to the perennial parts, because they showed a clear variation over the year. Vegetative development declined from June to October, and increased from October to February, when maximum median values of thallus height, total dry mass, non-perennial parts dry mass, and degree of branching were reached. This pattern coincided with those described for other species of the genus from warm temperate regions. Thallus height, a usually employed character in other phenological studies of Sargassum, showed lower coefficient of variation (53.2%) than those related to dry mass (72.0% to 182.3%). Peak of reproduction occurred from June to August, according to the following variables: fertile primary lateral branches number and dry mass and receptacles dry mass. Non-perennial parts dry mass and receptacles dry mass are recommended for phenological studies of S. vulgare. This methodological procedure avoids the sampling of the whole individual and warrants its regeneration from the perennial parts.

Challenges in the research and development of new human vaccines

The field of vaccinology was born from the observations by the fathers of vaccination, Edward Jenner and Louis Pasteur, that a permanent, positive change in the way our bodies respond to life-threatening infectious diseases can be obtained by specific challenge with the inactivated infectious agent performed in a controlled manner, avoiding the development of clinical disease upon exposure to the virulent pathogen. Many of the vaccines still in use today were developed on an empirical basis, essentially following the paradigm established by Pasteur, “isolate, inactivate, and inject” the disease-causing microorganism, and are capable of eliciting uniform, long-term immune memory responses that constitute the key to their proven efficacy. However, vaccines for pathogens considered as priority targets of public health concern are still lacking. The literature tends to focus more often on vaccine research problems associated with specific pathogens, but it is increasingly clear that there are common bottlenecks in vaccine research, which need to be solved in order to advance the development of the field as a whole. As part of a group of articles, the objective of the present report is to pinpoint these bottlenecks, exploring the literature for common problems and solutions in vaccine research applied to different situations. Our goal is to stimulate brainstorming among specialists of different fields related to vaccine research and development. Here, we briefly summarize the topics we intend to deal with in this discussion.