Cranial musculature of batoids: A standardized nomenclature.

Batoids (rays and skates) are cartilaginous fishes whose jaws are not articulated directly to the neurocranium. The only point of contact between them are the hyomandibular cartilages, resulting in a unique mandibular suspension called euhyostyly. Due to this decoupling of the jaws from the skull, muscles play an essential role in modulating mandibular movements during the feeding process, especially during mandibular protrusion. The main objectives of our study were: (1) to examine the mandibular musculature of eight batoid species from different orders in the Batoidea and (2) establish a standardized musclulature terminology for future comparative myological studies in batoids. For each muscle bundle, the general characteristics of each cranial muscle were described and their origin and insertions were identified. The number of muscle bundles differed intraspecifically. On the dorsal surface, we reported the first evidence of the presence of the precranial muscle (PCM) in U. halleri, as well as the ethmoideo-parethmoidalis muscle (ETM) in R. velezi, P. glaugostigma and Z. exasperata; in addition, the insertion of the spiracularis muscle (SP) extended to the ventral surface of the oropharyngeal tract in myliobatiforms. On the ventral surface of the head, both N. entemedor and M. californica exhibited additional muscles in the mandibular area. These muscles were renamed as part of the standardization of mandibular terminology: the depressor mandibularis minor (DMM) in N. entemedor and the adductor mandibulae profundus (AMP) in M. californica. The standardization of terminology is essential for futures studies of the mandibular apparatus in batoids, to facilitate the morphological description of muscles in species without anatomical accounts and for continuity in broader comparative analyses.

Inference for a discretized stochastic logistic differential equation and its application to biological growth.

In this paper, we present a method to adjust a stochastic logistic differential equation (SLDE) to a set of highly sparse real data. We assume that the SLDE have two unknown parameters to be estimated. We calculate the Maximum Likelihood Estimator (MLE) to estimate the intrinsic growth rate. We prove that the MLE is strongly consistent and asymptotically normal. For estimating the diffusion parameter, the quadratic variation of the data is used. We validate our method with several types of simulated data. For more realistic cases in which we observe discretizations of the solution, we use diffusion bridges and the stochastic expectation-maximization algorithm to estimate the parameters. Furthermore, when we observe only one point for each path for a given number of trajectories we were still able to estimate the parameters of the SLDE. As far as we know, this is the first attempt to fit stochastic differential equations (SDEs) to these types of data. Finally, we apply our method to real data coming from fishery. The proposed adjustment method can be applied to other examples of SDEs and is highly applicable in several areas of science, especially in situations of sparse data.

Biological notes on the reef stingray, Urobatis concentricus, an endemic species of Mexico.

This study found that the reef stingray Urobatis concentricus presents a matrotrophic aplacental viviparous reproduction with yolk sac and trophonemata formation. Growth of ovarian follicles occurs asynchronously and continuously with fecundity of three embryos per female. A maximum size of 58·4 cm total length and 37·6 cm disc width was recorded, corresponding to a mature female of 3 or 4 years of age.

Quality changes of fresh-cut kohlrabi sticks under modified atmosphere packaging.

The aim of this study was to determine the effect of different gas compositions on quality attributes and shelf life of kohlrabi sticks stored in modified atmosphere up to 14 d at 0 degrees C. Two commercial films were tested: oriented polypropylene (OPP) and amide-polyethylene (amide-PE). As a control, a microperforated OPP film was used. In order to study the changes in metabolic activity by minimal processing, the respiration rate and ethylene production at 0 degrees C were monitored for both intact stems and sticks. Changes in color, chemical parameters, sugars and organic acid contents, and sensorial quality of kohlrabi sticks were evaluated. An initial ethylene production of sticks was 13-fold higher than that of intact stems; meanwhile CO(2) production was 2-fold higher. However after 4 d of storage, a similar respiration rate for stems and sticks was found. Also the ethylene production of sticks and stems was steady around 15 to 20 nL/kg(/)h after 10 d. Kohlrabi sticks showed a little change in chemical parameters and very low weight losses during cold storage. Sticks under an equilibrium atmosphere of 7 kPa O(2) and 9 kPa CO(2) at 0 degrees C reached by amide-PE kept an acceptable sensorial quality for 14 d.

Extending the shelf life of kohlrabi stems by modified atmosphere packaging.

Kohlrabi stems (without leaves) were stored under modified atmosphere packaging (MAP) for 60 d at 0 degrees C. An additional retail sale period of 3 d at 12 degrees C after each cold storage evaluation (30 and 60 d) was applied. Under high relative humidity (RH) and 0 degrees C, the stems showed low metabolic activity, as no changes in sugars and organic acids were found. From day 21 at 0 degrees C, air-stored stems showed a yellowing of stalks and later they fell down. This disorder severely affected the appearance of stems. A gas composition of 4.5 to 5.5 kPa O(2) plus 11 to 12 kPa CO(2) was reached using antimist oriented polypropylene plastic bags of 20-mum thicknesses. The stems in MAP conditions kept a high sensorial quality. It was enough for commercial purpose of 2 mo. The storage of kohlrabi stems in plastic bags, either MA or in perforated (control) packages, provided an additional protection reducing physical damage. The MAP conditions delayed the weight loss and development of bacterial soft and black rot, extending the shelf life of kohlrabi stems to 60 d at 0 degrees C plus 3 d at 12 degrees C. Stems are not chilling injury sensitive.

Validation of predictive growth models describing superatmospheric oxygen effects on Pseudomonas fluorescens and Listeria innocua on fresh-cut lettuce.

Two microbial growth models predicting the growth of Pseudomonas fluorescens and Listeria innocua at superatmospheric oxygen and carbon dioxide concentrations at 7 degrees C were validated on fresh-cut butterhead lettuce. Cut lettuce was inoculated with the same strain of L. innocua as the in vitro experiments. The P. fluorescens strain was tagged with a gene encoding green fluorescent protein (GFP) in order to distinguish the inoculated strain from contaminating Pseudomonaceae. Also growth of aerobic mesophilic and lactic acid bacteria was monitored during the experiments. The suggested P. fluorescens model was appropriate to predict growth on cut lettuce. L. innocua on the other hand, grew considerably slower under in vivo circumstances than predicted. CO(2) had a growth promoting effect on L. innocua growing on cut lettuce, whereas in vitro an inhibiting effect was observed. Validation parameters are calculated and hypotheses to explain the discrepancy between predicted and observed growth of L. innocua are provided.

General characteristics of the diet of Trachinotus paitensis (Teleostei: Carangidae) from San Ignacio Lagoon, Baja California Sur, Mexico.

The food habits of Trachinotus paitensis, in San Ignacio Lagoon B.C.S., Mexico, were investigated. We observed that T. paitensis is carnivorous, feeding mainly on benthic invertebrates (the gastropods Anachis spp., Bittium spp., and the crustacean larvae). We concluded that T. paitensis is an opportunist predator that impacts mainly on epibenthic invertebrates.