Melanotropins: Pars Intermedia Structure and Function
Mac E. Hadley in The Melanotropic Peptides, 1988
The term “fish” covers several groups of vertebrates; within this group is the lamprey, a cyclostome, whose PI is posterior to the PD and fused with the overlying neural lobe. Only a thin connective tissue septum with capillary plexus separates the PI from the neural lobe. In the elasmobranchs, there is a very large posterior PI which is actually invaded by the neurohypophysis to form a fused neuro-intermedia (neuro-intermediate lobe). The degree of intermingling of the two varies with the species as does the arrangement of the PI cells themselves which may be arranged into a parenchymal mass or into lobes separated by a vascular connective tissue. Within the teleosts, the dominant fishes alive today, the distinctive feature is the interdigitation of the central neurohypophysis with the entire adenohypophysis, composed of the posterior PI and an anterior PD. These two are more closely fused than in tetrapods to form a compact adenohypophysis, with the interdigitations of the neurohypophysis with the PI usually more deep and elaborate than with the PD.
The Cycles of Life
Nate F. Cardarelli in The Thymus in Health and Senescence, 2019
Pinealectomy before metamorphosis may have a profound influence on the animal. PX prevents the metamorphosis of lamprey eel larva.199 Lampreys show developmental and archetectural changes in the pineal gland after passing from larval to adult forms.200 The insect brain counts time and number of molts through an unknown process.38 Saunders suggests that there are separate larval and adult clocks which act at different stages of development.201 Entrainment of the eclosion clock is through either a retinal or an extraretinal photoreceptor.202,203 Photoperiodic insects distinguish between long and short days, diapause being generally induced by the latter.203,204 Chippendale suggests that a brain-prothoracic-gland axis regulates pupal diapause.204 Thermoperiods and photoperiods interact in the induction of diapause at least in some insects.205 Low temperatures, “cryoscotophase”, may suppress the clock function that regulates the initiation or termination of diapause.
Animal Source Foods
Chuong Pham-Huy, Bruno Pham Huy in Food and Lifestyle in Health and Disease, 2022
Anadromous fish such as salmon, sturgeon, trout, shad, herring, sawfish, sea lamprey, and striped bass spend most of their adult life in the sea, but when they reproduce, they migrate into freshwater to spawn (deposit eggs). In contrast, catadromous fish, like anguillid eels, are born in a marine habitat, but migrate into freshwater area to grow and mature. When they become adults they return to the sea to spawn (23–24). Some wild freshwater fish mostly commonly consumed are: carp, catfish, charr, bluegill, pike, brown trout, perch, charr, crappie, and mooneye (23). Some common edible wild freshwater crustaceans are: crawfish (crayfish or freshwater lobster), shrimp (prawn), and freshwater crab. The main freshwater mollusks include around 1,200 species of freshwater bivalves (mussels, clams), and around 4,000 species of freshwater gastropods (snails) (25). Mussels have historically not only been eaten, but also used for tempering pottery and for making utensils, tools, and jewelry. Freshwater snails also serve as a food source for humans in many parts of the world.
The sine qua non of the fish invitrome today and tomorrow in environmental radiobiology
Published in International Journal of Radiation Biology, 2022
Nguyen T. K. Vo
Radioecological evidence suggests that organisms in wildlife are more radiosensitive than when they are studied in controlled environments in the laboratory (Garnier-Laplace et al. 2013). This is likely due to their exposure to other environmental stressors besides radiation that act as radiosensitizers. Complex mixtures of stressors can be difficult and time-consuming to separate one by one in the field. Conversely, by combining known or suspected stressors one by one with radiation challenge, multiple-stressor studies can be performed more quickly with fish cell lines in the laboratory. The end result is to determine possible outcomes and yield novel observations that can substantiate what is reported in the field. Two recent demonstrations of how fish cell lines can be used in multiple-stressor studies involving radiation were with the RTG-2 and eelB cell lines from rainbow trout and American eel, respectively. RTG-2 was used to study how environmental stressors such as heat shock and a wastewater contaminant can influence radiation responses (Sreetharan et al. 2018). eelB was used to show that the common field lampricide used to kill larval sea lampreys is a potential radiosensitizer for fish (Vo et al. 2019a). Using fish cell lines to study many classes of chemical and physical stressors that have not been systematically investigated in combination with radiation can be a research direction that is worth exploring.
How the parcellation theory of comparative forebrain specialization emerged from the Division of Neuropsychiatry at the Walter Reed Army Institute of Research
Published in Journal of the History of the Neurosciences, 2021
Sven O. E. Ebbesson
Some controversies are laid to rest by the recent publications from Grillner and coworkers at the Karolinska Institute in Stockholm (Grillner and Robertson 2016; Robertson et al. 2014; Suryanarayana et al. 2017, 2020), which have elegantly demonstrated in the lamprey that evolved some 500 million years ago, that lampreys have elements of a primordial neocortex. The results are similar to what I called neocortical equivalents (NE) in sharks, which appeared some 420 million years ago. Their studies showed unequivocally with multiple technologies that distinct visual and somatosensory thalamotelencephallic regions exist in this ancient vertebrate, confirming that the areas must have existed from the beginning of vertebrate evolution. They therefore showed, similar to the shark data (Cohen, Duff, and Ebbesson 1973; Ebbesson and Schroeder 1971; Graeber, Ebbesson, and Jane 1973), that these nonolfactory elements did not invade the telencephalon after elasmobranchs evolved, as Herrick (1948) asserted. These findings from the Grillner group support the conclusion that a visual and a somesthetic pallial area are common features of all vertebrate forebrains, and thus add weight to the theory. Results from studies of the lamprey brain (Suryanarayana et al. 2017, 2020) have shown that individual neurons in the primordial lamprey neocortex respond to primary visual and/or somatosensory input stimulations that are convergent with inputs from the olfactory lobe. These olfactory connections may have been lost by the time of the emergence of sharks and more modern vertebrates. Similar data are not available in other species.
Celebrating the research of Professor Shaun P Collin
Published in Clinical and Experimental Optometry, 2018
H Barry Collin
Shaun's work on cone monochromacy in sharks, follows on from his seminal work tracing the evolution of colour vision in early vertebrates, where he and his team discovered that jawless lampreys, the earliest representatives of the first vertebrates that date back over 500 million years, possess five different photoreceptor types and use a complex, pentachromatic cone‐based visual system to find hosts and navigate different light environments over their protracted lifecycle. In his Collin Medal address at the Southern Regional Conference in Melbourne in 2017, Shaun compared the visual systems of both lampreys and sharks, illustrating the marked evolutionary changes in visual abilities of these two ancient groups of fishes.
Related Knowledge Centers
- Cerebellum
- Diencephalon
- Gill
- Midbrain
- Reproductive Isolation
- Cerebrum
- Crown Group
- Hematophagy
- Species
- Scale