A postmortem study of the corpus callosum in the common minke whale (Balaenoptera acutorostrata)

Cetaceans diverged from terrestrial mammals approximately 53 mya and have evolved independently since then. During this time period, they have developed a complex nervous system with many adaptations to the marine environment. This study used stereological methods to estimate the total number and diameter of the myelinated fibers in the corpus callosum of the common minke whale (Balaenoptera acutorostrata) (n= 4). The total number of callosal fibers was estimated to 55.3 × 10⁶ (range: 49.0 × 10⁶–59.1 × 10⁶). Despite large variations of the callosal area (350–950 mm²), there was little variation in total fiber number. The fibers with diameters ranging from 0.822 to 1.14 μm were the most frequent, which is similar to results obtained in the human brain using the same method. There was no systematic distribution of large‐, middle‐, or small‐sized fibers along the rostrocaudal axis of the corpus callosum. This study indicated that the corpus callosum of the common minke whale is small and has few fibers compared to terrestrial mammals.     

MORPHOMETRIC COMPARISON OF MINKE WHALES BALAENOPTERA ACUTOROSTRATA FROM DIFFERENT AREAS OF THE NORTH ATLANTIC

Multivariate statistical analyses of 18 morphometric characters were performed in order to evaluate potential heterogeneity between predefined minke whale stock unit areas in the North Atlantic (West Greenland, Central, and Northeastern stocks). Results from principal component analyses suggested that the data cannot be regarded as random samples drawn from one uniform distribution. The overlap between groups was too substantial, however, to allow a firm conclusion concerning the question of isolated breeding stocks versus a large common breeding pool.     

The risks of learning: confounding detection and demographic trend when using count‐based indices for population monitoring

Theory recognizes that a treatment of the detection process is required to avoid producing biased estimates of population rate of change. Still, one of three monitoring programmes on animal or plant populations is focused on simply counting individuals or other fixed visible structures, such as natal dens, nests, tree cavities. This type of monitoring design poses concerns about the possibility to respect the assumption of constant detection, as the information acquired in a given year about the spatial distribution of reproductive sites can provide a higher chance to detect the species in subsequent years. We developed an individual‐based simulation model, which evaluates how the accumulation of knowledge about the spatial distribution of a population process can affect the accuracy of population growth rate estimates, when using simple count‐based indices. Then, we assessed the relative importance of each parameter in affecting monitoring performance. We also present the case of wolverines (Gulo gulo) in southern Scandinavia as an example of a monitoring system with an intrinsic tendency to accumulate knowledge and increase detectability. When the occupation of a nest or den is temporally autocorrelated, the monitoring system is prone to increase its knowledge with time. This happens also when there is no intensification in monitoring effort and no change in the monitoring conditions. Such accumulated knowledge is likely to increase detection probability with time and can produce severe bias in the estimation of the rate and direction of population change over time. We recommend that a systematic sampling of the population process under study and an explicit treatment of the underlying detection process should be implemented whenever economic and logistical constraints permit, as failure to include detection probability in the estimation of population growth rate can lead to serious bias and severe consequences for management and conservation.     

Optimization of HEK-293S cell cultures for the production of adenoviral vectors in bioreactors using on-line OUR measurements

The culture of HEK-293S cells in a stirred tank bioreactor for adenoviral vectors production for gene therapy is studied. Process monitoring using oxygen uptake rate (OUR) was performed. The OUR was determined on-line by the dynamic method, providing good information of the process evolution. OUR enabled cell activity monitoring, facilitating as well the determination of the feeding rate in perfusion cultures and when to infect the culture. Batch cultures were used to validate the monitoring methodology. A cell density of 10 × 10⁵ cell/mL was infected, producing 1.3 × 10⁹ infectious viral particles/mL (IVP/mL).To increase cell density values maintaining cell specific productivity, perfusion cultures, based on tangential flow filtration, were studied. In this case, OUR measurements were used to optimize the dynamic culture medium feeding strategy, addressed to avoid any potential nutrient limitation. Furthermore, the infection protocol was defined in order to optimize the use of the viral inoculum, minimizing the uncontrolled release of particles through the filter unit mesh. All these developments enabled an infection at 78 × 10⁵ cell/mL with the consequent production of 44 × 10⁹ IVP/mL, representing a cell specific productivity 4.3 times higher than for the batch culture.