New technical concept for alternating tangential flow filtration in biotechnological cell separation processes

Robust cell retention devices are key to successful cell culture perfusion. Currently, tangential flow filtration (TFF) and alternating tangential flow filtration (ATF) are most commonly used for this purpose. TFF, however, suffers from poor fouling mitigation, which leads to high filtration resistance and product retention, and ATF suffers from long residence times and cell accumulation. In this work, we propose a filtration system for alternating tangential flow filtration, which takes full advantage of the fouling mitigation effects of alternating flow and reduces cell accumulation. We have tested this novel setup in direct comparison with the XCell ATF® as well as TFF with a model feed comprising yeast cells and bovine serum albumin as protein at harsh permeate to feed flow conditions. We found that by avoiding the dead-end design of a diaphragm pump, the proposed filtration system exhibited a reduced filtration resistance by approximately 20% to 30% (depending on feed rate and permeate flow rate). A further improvement of the novel setup was reached by optimization of phase durations and flow control, which resulted in a fourfold extension of process duration until hollow fiber flow channel blockage occurred. Thus, the proposed concept appears to be superior to current cell retention devices in perfusion technology.     

Sexual dimorphism in a trophically polymorphic cichlid fish?

Sexual dimorphism in ecologically relevant traits is ubiquitous in animals. However, other types of intraspecific phenotypic divergence, such as trophic polymorphism, are less common. Because linkage to sex should often lead to balancing selection, understanding the association between sex and phenotypic divergence could help explain why particular species show high morphological variability. To determine if sexual dimorphism could be helping to maintain ecomorphological variation in a classic case of intraspecific trophic polymorphism, we examined the association between sex and morphological divergence in the cichlid Herichthys minckleyi. Although H. minckleyi with enlarged molariform teeth on their pharyngeal jaws have been reported to more commonly be male, we did not find an association between sex and pharyngeal morphotype. Sex was associated with divergence in body size (as measured through standard length). But, sex was not associated with any of the other trophic traits examined. However, pharyngeal morphotype did show an association with gut length, gape, and tooth number. Sexual dimorphism is not playing a central role in enhancing trophic diversity within H. minckleyi. J. Morphol. 276:1448–1454, 2015. © 2015 Wiley Periodicals, Inc.     

Functional morphology of durophagy in black carp,Mylopharyngodon piceus

The black carp, Mylopharyngodon piceus (Osteichthyes: Cyprinidae), crushes its snail and other molluscan prey with robust pharyngeal jaws and strong bite forces. Using gross morphology, histological sectioning, and X‐ray reconstruction of moving morphology (XROMM), we investigated structural, behavioral, and mechanical aspects of pharyngeal jaw function in black carp. Strut‐like trabeculae in their pharyngeal jaws support large, molariform teeth. The teeth occlude with a hypertrophied basioccipital process that is also reinforced with stout trabeculae. A keratinous chewing pad is firmly connected to the basioccipital process by a series of small bony projections from the base of the pedestal. The pharyngeal jaws have no bony articulations with the skull, and their position is controlled by five paired muscles and one unpaired median muscle. Black carp can crush large molluscs, so we used XROMM to compare pharyngeal jaw postures as fish crushed ceramic tubes of increasing sizes. We found that black carp increase pharyngeal jaw gape primarily by ventral translation of the jaws, with ventral rotation and lateral flaring of the jaws also increasing the space available to accommodate large prey items. A stout, robust ligament connects left and right jaws together firmly, but allows some rotation of the jaws relative to each other. Contrasting with the pharyngeal jaw mechanism of durophagous perciforms with fused left and right lower pharyngeal jaws, we hypothesize that this ligamentous connection may serve to decouple tensile and compressive forces, with the tensile forces borne by the ligament and the compressive forces transferred to the prey. J. Morphol. 276:1422–1432, 2015. © 2015 Wiley Periodicals, Inc.     

On the maxillary nerve

The trigeminal, the fifth cranial nerve of vertebrates, represents the rostralmost component of the nerves assigned to pharyngeal arches. It consists of the ophthalmic and maxillomandibular nerves, and in jawed vertebrates, the latter is further divided into two major branches dorsoventrally. Of these, the dorsal one is called the maxillary nerve because it predominantly innervates the upper jaw, as seen in the human anatomy. However, developmentally, the upper jaw is derived not only from the dorsal part of the mandibular arch, but also from the premandibular primordium: the medial nasal prominence rostral to the mandibular arch domain. The latter component forms the premaxillary region of the upper jaw in mammals. Thus, there is an apparent discrepancy between the morphological trigeminal innervation pattern and the developmental derivation of the gnathostome upper jaw. To reconcile this, we compared the embryonic developmental patterns of the trigeminal nerve in a variety of gnathostome species. With the exception of the diapsid species studied, we found that the maxillary nerve issues a branch (nasopalatine nerve in human) that innervates the medial nasal prominence derivatives. Because the trigeminal nerve in cyclostomes also possesses a similar branch, we conclude that the vertebrate maxillomandibular nerve primarily has had a premandibular branch as its dorsal element. The presence of this branch would thus represent the plesiomorphic condition for the gnathostomes, implying its secondary loss within some lineages. The branch for the maxillary process, more appropriately called the palatoquadrate component of the maxillary nerve (V₂), represents the apomorphic gnathostome trait that has evolved in association with the acquisition of an upper jaw. J. Morphol. 275:17–38, 2014. © 2013 Wiley Periodicals, Inc.     

Increasing the resolution of polyacrylamide gel electrophoresis by varying the degree of gel crosslinking

Resolution of polyacrylamide gel electrophoresis may be substantially improved by taking advantage of the gel sieving effects of varying concentrations of bisacrylamide crosslinker. A dilution procedure is described which permits simultaneous variation of both total acrylamide concentration and percent crosslinking within a single linear regression analysis.This work was supported by NSF Grant 10584 and NIH Grant 23504.     

Morphological variation of the palatal organ and chewing pad of catostomidae (Teleostei: Cypriniformes)

We studied the morphology and shape variation of the palatal organ and chewing pad of sucker fishes, family Catostomidae. The palatal organ is a muscularized structure that forms a large mass on the roof of the posterior part of the buccopharyngeal cavity in cypriniform fishes. It functions in coordination with the branchial arches to separate food items from inorganic debris during feeding. The palatal organ exhibits considerable variability in morphology among catostomids. It is shorter, narrower, and thinner in species of the subfamily Cycleptinae (e.g., Cycleptus elongatus) than in other catostomid subfamilies. The thickest and widest palatal organ is seen in species of the subfamily Ictiobinae (e.g., Ictiobus cyprinellus). The shape and size of the palatal organ generally varies between these extremes in species of subfamily Catostominae (e.g., Catostomus and Moxostoma species). Principal components analysis and analysis of variance has differentiated means of various palatal organ measurements for each monophyletic subfamily and tribe of Catostomidae with statistical significance. These results corroborate previously established typological classification of catostomids based on pharyngeal tooth count, pharyngeal tooth morphology, and diet. A keratinized chewing pad forms on the posterior surface of the palatal organ in catostomids or on a skeletal process in cyprinids and serves as an occlusion surface for pharyngeal teeth. The chewing pad is lunate in catostomids and generally ovoid in cyprinids. It is absent from the species of loaches (e.g., botiids, cobitids, and nemacheilids) and gyrinocheilids examined. A synonymy of terms used in the past to describe the palatal organ and chewing pad of Cypriniformes is provided. J. Morphol., 2011. © 2011 Wiley‐Liss, Inc.     

Suitability of pharyngeal bone measures commonly used for reconstruction of prey fish length

Three measures (gape, tip and tooth row) of pharyngeal bones from 13 Eurasian cyprinid fish species caught in north-eastern Germany were used to establish species specific bone measurelength relationships for reconstruction of prey fish length. Left and right bones were symmetrical in the case of gape, tip and length of tooth row in 69, 46 and 8%, respectively. Gape and tip showed significantly lower maximum values of relative error than the tooth row measure. A comparison of bone measures established for roach Rutilus rutilus (L.) and bream Abramis brama (L.) from north-eastern and from southern Germany showed significant differences. Left and right bone measure-length relationships are not generally identical. Gape and tip measures allow more accurate back-calculation of length than tooth row measures and locality specific relationships should be established.     

Effect of stage of maturity of grass at harvest on intake,chewing activity and distribution of particle size in faeces from pregnant ewes

This study was conducted to investigate the effect of stage of maturity at harvest on the intake of grass silage, eating and ruminating activity and the distribution of faecal particle size in ewes during late pregnancy. A total of 18 Swedish Finull × Dorset 85 ± 8 kg (mean ± s.d.) ewes bearing twins were randomly assigned to three dietary treatments 6 weeks before lambing. The treatments included ad libitum feeding with early harvested (EH), medium harvested (MH) or late harvested (LH) primary-growth grass silage with 45%, 58% and 63% NDF on a dry matter (DM) basis, respectively. Intake and chewing activity were recorded and faeces were sampled over 4 continuous days for each individual ewe. The faeces samples were washed in nylon bags, freeze dried and sieved with pore sizes from 2.4 mm to 0.1 mm; particles less than 0.1 mm in size were also collected. Subsamples of each sieving fraction were scanned and the dimensions of the individual particles in each sieving fraction were measured by image analysis. In addition, the number of particles longer than 7 mm was counted from the particles retained on a sieve with a pore size of 2.4 mm using a simple wet sieving technique. The time spent eating and ruminating per kg of DM intake was affected by the stage of maturity at harvest; it was shorter in ewes fed EH compared with ewes fed MH and LH (P < 0.05). In comparison with feeding LH, feeding EH resulted in the retention of a larger proportion of particles in the lower and upper sieve fractions (<0.2 mm and >1 mm, respectively, P < 0.01), a smaller mean particle size (P < 0.05) and a smaller mean particle width in faeces (P < 0.01). The results from the simple wet sieving technique confirmed the results from dry sieving and image analysis, showing a higher number of large particles in faeces from ewes fed the EH compared with the ewes fed the MH and LH (P < 0.001). In conclusion, the distribution of faecal particle size might be considered as a footprint of the characteristics of forage fibre eaten by ewes.     

Some ultrastructural observations on the microfilaria of Breinlia sergenti-the pharyngeal thread and Innenkorper

Some ultrastructural observations on the microfilaria of Breinlia sergenti—the pharyngeal thread and Innenkorper.International Journal for Parasitology4: 375–382. The fine structure of the pharyngeal thread and the Innenkorper (inner body) of the microfilaria of Breinlia sergenti is described. The pharyngeal thread is seen as an elongated cuticular structure with associated nervous elements while the Innenkorper is sac-like in appearance. A possible function related to the transfer and storage of nutrient material is assigned to these structures.