For comparison, we also tested four Mexican blind tetra characins from a commercial stock most of these stocks originally came from La Chica Cave. In order to investigate the melanin synthesis in these fishes in vitro experiments were performed, supplying L-DOPA to mm 2 caudal-fin clippings and observing whether cells with melanin inclusions were observed or not.
Due to the small size of the fish, fin fragments of different individuals except for the relatively large A. Each individual was tested once. We used the same general steps of the method described by Mishima and Hirobe Fragments of the upper lobe of caudal fins were removed from alive, non-anesthetized fish, using small surgical scissors. In no case, pigment cells were observed in control fish.
No intra- or inter-population variations were observed for the studied species.
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No pigmented cells were visible in the controls. Selected fin fragments are shown in Figs. These conclusions were based on traditional genetic studies using lineage crossings. A different approach, based on developmental molecular biology, was recently applied by McCauley et al. During the last two decades, the molecular approach has been increasingly used in genetic studies on pigmentation disorders such as the oculocutaneous albinism OCA , characterized by a reduced or absent biosynthesis of melanin pigment in melanocytes of the skin, hair follicles and eyes.
OCA types 2and 4 are caused by disruption of the sorting of functional tyrosinase to melanosomes. Thus the types 2 and 4 of OCA conditions would correspond to the so-called "tyrosinase-positive albinism". On the other hand, the presence of melanin cells, evidenced after the administration of L-DOPA to samples from Stygichthys typhlops, Ancistrus formoso, Rhamdiopsis sp, "Taunayia" sp.
Results and Discussion
On the other hand, the discontinuous distribution of the depigmented versus pigmented phenotypesin T. Otherwise, the high proportion of completely depigmented fish is inconsistent with the expected for the frequency of this extreme phenotype within a polygenic system.
Because the depigmented individuals are irresponsive to L-DOPA, mechanisms might be involved in the loss of their ability to synthesize melanin. Some possibilities include gene mutations leading to an increase of tyrosinase degradation, disruption of tyrosinase function, or the loss of the ability to convert L-DOPA into melanin due to a blocking of some step downstream of L-DOPA synthesis in the melanogenic pathway of these albino specimens. In mammals, similar condition results from the disruption of tyrosinase or TRP-1 function and causes oculocutaneous albinism OCA type 1 tyrosinase-negative or type 3 TRP-1 , with absence or reduction of melanin pigment by melanocytes in the skin, hair follicles, and eyes.
However, intensive bioquemistry and genetic research are required in order to classify pigmentation disorders of these teleosts according to the level of knowledge of mammalian disorders. It is noteworthy that an individual variation in color is observed within the pigmented part of the T. Therefore, it is reasonable to infer that the depigmented part of the population is also heterozygous in relation to the polygenic system, but the melanin cells are colorless.
The case with Rhamdiopsis sp. Rhamdiopsis sp. Bockmann, pers. The high degree of morphological specialization of Rhamdiopsis sp. In conclusion, our data point to the occurrence of different genetic mechanisms of melanin reduction in troglobitic fishes, which may co-exit in the same species: a polygenic system would be involved in the differentiation of melanophores, determining their density in the skin, and monogenic systems would be involved in the ability to synthesize melanin, which could be lost due to the blocking of different steps in this syntheses.
Both morphological and physiological melanin reduction is observed in T. For a first approach to this problem, tests in vitro with L-DOPA using fin clippings are simple, quick and informative, and particularly adequate to the generally small subterranean fish populations, because fins regenerate, thus it is not necessary to dispose the fish and repetitions are possible using the same specimens. Hirobe, T. Origin of melanosome structures and cytochemical localizations of tyrosinase activity in differentiating epidermal melanocytes of newborn mouse skin.
Journal of Experimental Zoology, Jeffery, W. Convergence of pigment regression in cave animals: developmental, biochemical, and genetic progress toward understanding evolution of the colorless phenotype. In: Moldovan, O. Jimbow, K.
Hua, P. Gomez, K.
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Hirosaki, K. Soda, T. Salopek, H. Matsusaka, H. Intracellular vesicular trafficking of tyrosinase gene family protein in eu- and pheomelanosome biogenesis. Pigment Cell Research, 13 sup. Mattox, G. Bichuette, S. This is a list of books which represent that work's first publication in book form.
This list does not include limited edition reprints, unless those editions are considered definitive author revisions of the original. From Wikipedia, the free encyclopedia. Categories : American speculative fiction publishers Horror book publishing companies Book publishing companies based in Michigan Science fiction publishers Small press publishing companies Publishing companies established in Namespaces Article Talk. Views Read Edit View history. Our results indicate an effect of social interaction in the expression of biological rhythms even in solitary animals.
Keywords: Ctenomyidae, Tuco-tuco, Social synchronization, Around-the-clock activity, Circadian rhythm. Social modulation of circadian rhythms  has been reported in several species, such as birds , rodents , bats , primates  and invertebrates . For a review, see [2,21]. This synchronization could be mediated by non-photic social cues, such as pheromones, sound and sight of conspecifics.
Tuco-tucos genus Ctenomys are herbivorous subterranean rodents endemic to South America. The genus is very speciose, with circa 60 described species, and can be found in a great variety of habitats . Despite evidence of sociality in some species C. Among non-social species, reports of more than one animal found together are rare and restricted to mating couples or females with young [25,26].
In this context, we report that a single birth event unexpectedly disrupted the robust nocturnal wheel-running activity rhythm of a group of 13 singly housed tuco-tucos Ctenomys sp captured in La Rioja province in Argentina. This peculiar response of the other captive animals, which lasted one entire day on average for females and longer for males, revealed that circadian rhythms can be modulated by social cues, in this solitary subterranean rodent.
An experiment was performed to test if this social modulation was intermediated by acoustic cues using playbacks of a pup vocalization. The population of Ctenomys found in the area is called the Anillaco tuco-tuco however, species determination has not been completed yet. Morphological, molecular and genetic analysis for this purpose are ongoing.
During the time of this case report, tuco tucos were caught year-round for various experiments using PVC tube traps placed at fresh surface mounds inside natural burrows. Every procedure followed the guidelines of the American Society of Mammalogists for animal care and handling . In the animal facility x cm , 13 adult animals 10 females and 3 males were kept individually in acrylic cages 53x27 cm and 29 cm high equipped with wire mesh lids and stainless steel running wheels.
Food fresh vegetables, seeds and rabbit pellets was offered daily at random times.
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Because tuco-tucos obtain water from food, water was not provided. Graphical output actograms and rhythm analysis were carried out using the El Temps software A. An unusual event of rhythm disruption was registered in several individuals: On October 22th , one of the females captured in July of the same year gave birth to two pups in the animal facility. The female abandoned the pups, which wandered around the cage for two days until perishing. One male 10 also displayed this continuous 24 h activity but then totally interrupted activity for three continuous days.
Two other males displayed longterm arrythmicity that lasted for at least 14 days 20 and 26 and rhythmicity was then restored without an observable phase shift data not presented. One female died after running all day and night Only two females maintained intact nocturnal rhythmicity 15 and 18 Fig. To test if acoustic stimuli emitted by the pups can cause the observed rhythmic disruption, another new set of 10 adult animals 5 females and 5 males were exposed to playbacks of vocalizations from a new pup.
The recorded vocalization consisted of calls emitted by a pup captured with the approximate age of 15 days. This estimation was based on its weight 29 g , size of incisive and time during which care-eliciting calls were recorded. Upon capture the pup was placed in a lab terrarium 60 cmx cm and 50 cm high , filled with wood ships and diverse plastic and cardboard tubes used as burrows and nest. Ad lib feeding included sweet potatoes, carrots, sunflower seeds, oatmeal, rabbit pellets as well as items of its natural diet collected weekly from the field Larrea sp, Opuntia sp, Parkinsonia praecox.
Vocalizations were recorded using a Zoom H4n digital hand recorder system with built-in microphones frequency range Sounds were recorded at a sample rate of The care-elicitation vocalization recorded in this specimen is very similar to those recorded for Ctenomys talarum , however determination of the details of this similarity is an ongoing study Amaya et al.
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A three-min interval of these recordings in the terrarium was selected, based on its long duration, frequent and clear vocalizations, as well as free of background noise, to be used to assemble the h playback section used in this experiment. Two different sequences were mounted for the playback sections. In the first non-continuous calls the selected three-min interval was repeated during 30 min followed by a min interval of silence; this continued for the remaining 9 h.
In the second sequence continuous calls , 30 min interval of silence was eliminated and vocalizations were played throughout the h pulse. Intensity was the same in both sequences. Two loudspeakers were placed in the animal facility orientated towards the 10 experimental animal cages in such a way that the distance between them and the cages was always within m.
Playback sections occurred in two times along the light-dark cycle, one along the light-phase, from to h, and the second along the dark-phase, from to However only the 5-h middle section was used for analysis to avoid potential effects due to the presence of the experimenters in the limits of the playback interval.
Activity levels during the 5 h intervals were quantified as the total number of 5-minute bins displaying a detected wheel-running revolution. The experiment was then repeated using the continuous calls and the same comparison was done in the expression of running-wheel revolutions. Additionally, in this second experiment, general activity levels were also registered using infrared sensors located in the middle-top of each cage, which are sensible to subtle movements.
We then increased only the frequency of calls in the second experiment. In this context, it's notable that several experiments had already been conducted with tuco-tucos under constant darkness conditions [31, see this work also for more details on laboratory conditions; ], but never before had any mutual synchronization among individuals been detected. The animals cannot see each other and we also know that they do not react to the sight of others, even when two translucent cages are placed side-by-side.
Their cages were not, however, isolated in terms of sound or smell, suggesting that these factors could have mediated the observed rhythmic changes. Changes in rhythmic patterns intermediated by chemical cues have been shown, for instance, in social interactions between two rodent Acomys species  and among socially interacting Octogon degus individuals .
It has been reported that through close inspection of urine, feces or dirt, tuco-tucos can discriminate chemical cues and use them to assess the reproductive condition of conspecifics [37,38]. In this sense, social modulation of rhythmicity could potentially be mediated by chemical factors in tuco-tucos, although such phenomenon has not been described before. Acoustic signals in tuco-tucos seem to be particularly important in social interactions, as they extensively use vocalizations to communicate between individuals in the same burrow as well as in different burrows [26,28,].
This genus displays complex vocalization patterns, which have been described for C. One of the vocalizations described is the high frequency distress call emitted by newborn pups when far from their mother [40,42,43]. Surprisingly, males were also affected by the social event however, the response was different and longer-lasting. They displayed at least 14 days of arrythmicity before resuming normal rhythmicity.
Another possibility is that the mother emitted signal that affected the males.
Materials and Methods
The fact that the female abandoned the pups is an indication that this female was stressed maybe because the captivity conditions were not ideal for rearing pups or because she detected the presence of other animals. The presence of other animals during parturition in a solitary species may be a strong threatening stimulus. It is also interesting to note that, unlike most reports of social synchronization in long-cohabiting rodent species [8,12], the around-the-clock activity of tuco-tucos was immediately triggered by unpredictable social stimuli.
Results of the playback tests were not consistent with the observed around-the-clock phenomenon, which could not be reproduced by merely imposing the pup sound. It could be that the vocalization that was recorded did not correspond to the particular newborn pattern that triggered the rhythmic disruption of tucos. Besides this, our results can indicate that the vocalization alone, if any, was not the triggering stimulus, rescuing the role of the olfactory and perhaps other sensory components. We could be sure, however, with these results, that the activity rhythm of tuco-tucos is not easily modulated by sound.