Diatoms and the ecological conditions of their growth in sea ice in the arctic ocean

A summer field survey off Point Barrow, Alaska, revealed that Arctic sea ice develops a growth of phytoplanktonic diatoms. The diatoms are found in a brine solution in microfissures between ice crystals on the underside of the ice. The chlorophyll content of this layer is 100 times more than that of the surrounding sea waters; this has led to a hypothesis that a considerable fraction of the primary production of the Arctic Sea may be carried out in sea ice, especially during the spring and early summer months.     

Endoscopic transcervical intrauterine artificial insemination in Labrador Retriever bitches

Besides post-thawing reduced semen quality, there are some difficulties in the execution of the endoscopic transcervical intrauterine artificial insemination (AI) with frozen-thawed semen in bitches. Therefore, the aims of the present study were to evaluate behavioral and reproductive parameters (i.e., vaginal cytology and serum progesterone level) to determine time of insemination and to investigate the particularities and difficulties of this technique in bitches using fresh semen. Ten Labrador Retriever bitches were submitted to three endoscopic transcervical intrauterine AIs (with 48 h intervals). Oestrus and ovulation period were established by behaviour evaluation, progesterone assays and vaginal cytology, enabling optimal timing for AI during oestrus. During AI, the following aspects were evaluated: cervical os catheterization difficulty, semen deposition resistance, occurrence of semen backflow, and time required to perform the AI. In this study, it was possible to catheterize the cervical os in all bitches, with different degrees of difficulty, by manipulating the equipment to allow cervical visualization and catheter introduction in the cervical canal. Serial serum progesterone assays enabled estimation of LH surge day, and thus of ovulation. The pregnancy rate was 90%, with a litter size of 5.0 ± 2.6 puppies per bitch. It was concluded that the difficulties in the execution of the endoscopic transcervical intrauterine AI technique in Labrador Retriever bitches were minimized by the equipment manipulation and practical experience.