A first survey on the biochemical composition of egg yolk and lysozyme-like activity of egg envelopment in the cuttlefish Sepia officinalis from the Northern Adriatic Sea (Italy).

The cuttlefish Sepia officinalis is an important fishery resource in the Northern Adriatic Sea (Italy). During reproduction, fertilised eggs are released by adult females in coastal waters and embryo development can take over two months. During this period, embryos rely on nutrients and other substances, such as immune factors, provided by the female in egg yolk. In cephalopods in general, and specifically in the common cuttlefish, little information is available on yolk biochemical composition and substances included in egg envelopment. In the present study, the main biochemical components of egg yolk and the presence of antimicrobial substances in egg envelopment of S. officinalis were determined for the first time. Statistically significant differences in total egg weight and egg yolk weight were observed among batches from different females. Egg and yolk weights were positively correlated, with yolk representing the 13% (±5%) of the total egg weight. Total proteins were the main biochemical component (46%) of egg yolk, followed by total carbohydrates plus glycogen (39%) and lipids (15%). Statistically significant differences among batches were recorded in egg yolk total protein amounts, lipids, carbohydrates and glycogen, but no correlations were found between egg yolk weight and the biochemical components. The Petri dish and the quantitative spectrophotometric assays revealed the presence of lysozyme-like activity in egg gelatinous envelopment.

Movement seasonality in a desert-dwelling bat revealed by miniature GPS loggers.

BACKGROUND: Bats are among the most successful desert mammals. Yet, our understanding of their spatio-temporal dynamics in habitat use associated with the seasonal oscillation of resources is still limited. In this study, we have employed state-of-the-art lightweight GPS loggers to track the yellow-winged bat Lavia frons in a desert in northern Kenya to investigate how seasonality in a desert affects the a) spatial and b) temporal dimensions of movements in a low-mobility bat. METHODS: Bats were tracked during April-May 2017 (rainy season) and January-February 2018 (dry season) using 1-g GPS loggers. Spatial and temporal dimensions of movements were quantified, respectively, as the home range and nightly activity patterns. We tested for differences between seasons to assess responses to seasonal drought. In addition, we quantified home range overlap between neighbouring individuals to investigate whether tracking data will be in accordance with previous reports on territoriality and social monogamy in L. frons. RESULTS: We obtained data for 22 bats, 13 during the rainy and 9 during the dry season. Home ranges averaged 5.46 ± 11.04 ha and bats travelled a minimum distance of 99.69 ± 123.42 m/hour. During the dry season, home ranges were larger than in the rainy season, and bats exhibited high activity during most of the night. No apparent association with free water was identified during the dry season. The observed spatial organisation of home ranges supports previous observations that L. frons partitions the space into territories throughout the year. CONCLUSIONS: Our results suggest that, in low-mobility bats, a potential way to cope with seasonally harsh conditions and resource scarcity in deserts is to cover larger areas and increase time active, suggesting lower cost-efficiency of the foraging activity. Climate change may pose additional pressures on L. frons and other low-mobility species by further reducing food abundances.